Interventions for preventing hamstring injuries

Interventions for preventing hamstring injuries (Review)
Goldman EF, Jones DE
This is a reprint of a Cochrane review, prepared and maintained by The Cochrane Collaboration and published in The Cochrane Library
2010, Issue 1
http://www.thecochranelibrary.com
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
TABLE OF CONTENTS
HEADER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PLAIN LANGUAGE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AUTHORS’ CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ACKNOWLEDGEMENTS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHARACTERISTICS OF STUDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DATA AND ANALYSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 1.1. Comparison 1 Strengthening protocols versus control, Outcome 1 Participants sustaining hamstring injury.
Analysis 1.2. Comparison 1 Strengthening protocols versus control, Outcome 2 Participants sustaining hamstring injury:
alternative analyses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 1.3. Comparison 1 Strengthening protocols versus control, Outcome 3 Participants sustaining lower limb
injuries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 2.1. Comparison 2 Manual therapy protocol versus control, Outcome 1 Participants sustaining a hamstring
injury. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 2.2. Comparison 2 Manual therapy protocol versus control, Outcome 2 Participants sustaining lower limb
injuries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 3.1. Comparison 3 Proprioceptive training protocol versus control, Outcome 1 Incidence of hamstring injury.
Analysis 3.2. Comparison 3 Proprioceptive training protocol versus control, Outcome 2 Incidence of hamstring injuries adjustment for clustering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 3.3. Comparison 3 Proprioceptive training protocol versus control, Outcome 3 Incidence of all lower limb
injuries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 3.4. Comparison 3 Proprioceptive training protocol versus control, Outcome 4 Incidence of all lower limb injuries
- adjustment for clustering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 4.1. Comparison 4 Warm-up, cool-down and stretching protocol versus control, Outcome 1 Incidence of
hamstring injury. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 4.2. Comparison 4 Warm-up, cool-down and stretching protocol versus control, Outcome 2 Incidence of all lower
limb injuries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ADDITIONAL TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
WHAT’S NEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CONTRIBUTIONS OF AUTHORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DECLARATIONS OF INTEREST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SOURCES OF SUPPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
INDEX TERMS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
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[Intervention Review]
Interventions for preventing hamstring injuries
Elliott F Goldman1 , Diana E Jones2
1 Synergy
Healthcare, Bedlington, UK. 2 School of Health, Community and Education Studies, Northumbria University, Newcastle
upon Tyne, UK
Contact address: Elliott F Goldman, Synergy Healthcare, 1-4 Stokers Buildings, Front Street East, Bedlington, Northumberland, NE22
5DS, UK. [email protected].
Editorial group: Cochrane Bone, Joint and Muscle Trauma Group.
Publication status and date: Edited (no change to conclusions), published in Issue 2, 2010.
Review content assessed as up-to-date: 28 February 2009.
Citation: Goldman EF, Jones DE. Interventions for preventing hamstring injuries. Cochrane Database of Systematic Reviews 2010, Issue
1. Art. No.: CD006782. DOI: 10.1002/14651858.CD006782.pub2.
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
ABSTRACT
Background
Some sports, such as football, have a high incidence of hamstring injuries. Various interventions targeting the prevention of such injuries
are in common use.
Objectives
To assess the effects (primarily, on the incidence of hamstring injuries) of interventions used for preventing hamstring injuries in
physically active individuals.
Search methods
We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (to December 2008), the Cochrane Central
Register of Controlled Trials (The Cochrane Library, 2008, Issue 4), MEDLINE and other databases (to December 2008), reference
lists and clinical trials registers.
Selection criteria
Randomised or quasi-randomised trials of interventions for preventing hamstring injuries were included; as were trials testing interventions for the prevention of lower-limb injuries, provided that hamstring injuries were reported. Secondary outcomes included
compliance, severity and the occurrence of other leg injuries.
Data collection and analysis
Two authors independently screened search results, assessed methodological quality and extracted data. Risk ratios (RR) and 95%
confidence intervals (95% CI) were calculated for dichotomous variables and are reported for individual and pooled data.
Main results
Seven randomised controlled trials involving 1919 participants were included. All trials involved people, predominantly young adults,
participating in regular sporting activities. Some trials were compromised by poor methodology, including lack of blinding and
incomplete outcome data.
Four trials, including 287 participants, examined interventions directly targeted at preventing hamstring injuries. Three of these trials,
which tested hamstring strengthening protocols, had contradictory findings, with one small trial showing benefit (although the control
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
1
rate of mainly minor hamstring injury was unusually high). The other two trials found no benefit, with a greater incidence of hamstring
injury in the intervention group. One unpublished and underpowered trial provided some evidence that manual therapy may prevent
lower-limb muscle strain (RR 0.13, 95% CI 0.02 to 0.97), although the finding for hamstring injury did not reach statistical significance
(RR 0.21, 95% CI 0.03 to 1.66).
Three trials testing interventions for preventing lower limb injuries for which data for hamstring injury were available found no
statistically significant effect for hamstring injury for either proprioceptive protocols (two cluster randomised trials) or a warm up/cool
down and stretching protocol (one trial).
Authors’ conclusions
There is insufficient evidence from randomised controlled trials to draw conclusions on the effectiveness of interventions used to prevent
hamstring injuries in people participating in football or other high risk activities for these injuries. The findings for manual therapy
need confirmation.
PLAIN LANGUAGE SUMMARY
Interventions for preventing hamstring injuries
Hamstring (muscles situated at the back of the thigh) injuries are common in sports such as football and basketball. These injuries are
often serious, causing pain, long rehabilitation times and a distinct proneness to re-injury. Various interventions targeting the prevention
of such injuries are in common use. This review set out to examine the evidence for the effectiveness of these interventions in preventing
hamstring injuries.
Seven randomised controlled trials involving a total of 1919 participants were included. All trials involved people, predominantly young
adults, participating in regular sporting activities. Some trials were compromised by poor methodology, including lack of blinding and
incomplete outcome data.
Four trials, including 287 participants, examined interventions directly targeted at preventing hamstring injuries. Three of these trials,
which tested hamstring strengthening protocols, had contradictory findings and we could not conclude whether strengthening exercises
of the hamstrings was beneficial or not. One small trial found that manual therapy (involving manipulation, massage and specific
stretches to joints and muscles of the spine and leg) may prevent injuries of leg muscles, including the hamstrings.
Three inconclusive trials tested interventions for preventing all leg injuries for which data for hamstring injury were available. Two
trials found no evidence for an effect for balance training on a wobble board (proprioceptive protocol). One trial found no evidence
for a warm up/cool down and stretching protocol for distance runners.
Based on currently available research findings, no specific intervention can be recommended for decreasing the risk of incurring
hamstring injuries.
BACKGROUND
Description of the condition
Hamstrings are a group of muscles of the posterior thigh which
cross both the hip and knee joints and are involved in thigh extension and knee flexion. The hamstring muscle group comprises
three separate muscles: semitendinosus, semimembranosus and bi-
ceps femoris. Hamstring injury is defined by the anatomical site
within the muscle that is affected, and injury must be present in
one or more of the component muscles. Hamstring injuries are
commonly classified as grades one, two and three, where severity increases with the grade of injury (Kellet 1986). Diagnosis is
based on patient history, including the cause of injury and clinical
findings of local pain and loss of function, demonstrated by palpation, range of motion and muscle testing (Kujala 1997). Magnetic
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
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resonance imaging (MRI) can provide further information on the
extent of injury (Brandser 1995). It is important to note that the
frequency and severity of injury may differ in adolescents from
that in skeletally mature people. Injuries occur in patterns unique
to the skeletally immature adolescent, reflecting their developing
bones and supporting ligamentous structures (Frank 2007).
Musculotendinous injuries usually occur as a result of either direct
or indirect trauma (Agre 1985). Direct trauma such as from a blow
results in muscle contusion (bruising). Indirect trauma can occur
as a result of alteration in the intensity or synergy of contraction,
resulting in a single powerful muscle contraction. Hamstrings are
capable of producing large forces (Garrett 1984; Noonan 1999)
that are most beneficial during periods of increased activity requiring bursts of speed or rapid acceleration and deceleration. Recent evidence has suggested that the hamstring muscles are most
vulnerable to injury during the rapid change from eccentric to
concentric function, such as where the leg decelerates to strike the
ground during running (Verrall 2001). (Concentric function is
where a muscle actively shortens in order to produce movement.
For example, concentric action of the quadriceps, the muscle at
the front of the thigh, straightens the knee to produce a kicking action. Eccentric function is where a muscle generates active tension
as it lengthens, braking a movement. For example, the hamstrings,
situated at the back of the thigh, would function eccentrically to
brake the kicking action.) Indirect trauma can also result from an
overstretch of the musculotendinous unit leading to a strain, tear
or avulsion (Agre 1985). It is generally claimed that strain injuries
most often occur near the musculotendinous junction (Garrett
1996).
Hamstring injuries are commonplace in many mainstream sports
and occupations involving physical activity (Kroll 1997). The initial Football Association Audit of Injuries study (Hawkins 2001)
found that 12% of all injuries reported over two seasons were
hamstring strains. A hamstring injury is likely to cause a professional footballer to miss approximately three matches or weeks of
play (Woods 2004). Hamstring injuries are often serious requiring rehabilitation and they tend to recur (Croisier 2004; Orchard
2002a). For instance, Orchard 2002b reported a high rate of recurrence in 34% of primary cases over the course of a Australian
football season.
The causes of hamstring injuries are complicated and multifactorial (Gleim 1997). In general, a distinction in risk factors has
been made between so-called intrinsic (person-related) and extrinsic (environment-related) risk factors (Inklar 1994; Taimela 1990;
Van Mechelen 1992). Intrinsic factors include hamstring muscle weakness, strength imbalances, fatigue, inadequate flexibility,
body mechanics and disturbed posture, poor running technique
and psychosocial factors (Agre 1985; Croisier 2002; Knapik 1992;
Worrell 1992). Extrinsic factors include unsatisfactory warm-up
and training procedures, fatigue related to enforced excessive activity, poor playing surfaces and unsuitable training and sports spe-
cific activities (Hawkins 1999; Safran 1988). Orchard 2001 suggested intrinsic factors are more predictive of muscle strain than
extrinsic factors. However, a recent systematic review (Foreman
2006) concluded that no single risk factor was found to have a
significant association with hamstring injury (although the review
was limited by the use of smaller cohort studies and the exclusion
of non-English papers). Understanding the individual risk factors
for injury is an important basis for developing preventive measures.
Description of the intervention
The prevention of hamstring injuries is an ongoing process where
intervention is necessary for as long as participants engage in the
physical activities that place them at risk. Many interventions are
widely employed by participants, trainers, coaches and therapists
specifically aiming to prevent such injuries. These include exercise
therapy to strengthen and lengthen the hamstring muscles, such as
stretching and strengthening exercises (Croisier 2002); neuromuscular injury prevention strategies including proprioceptive balance
training (Emery 2007; Turl 1998); chiropractic, spinal manipulative therapy (SMT) and correction of lumbar-pelvic biomechanics
(Hoskins 2005); muscle activation work to improve hip extension
motor patterns and running technique (Hoskins 2005); massage
and mobilisation to increase flexibility and range of movement
directed towards soft-tissues structures (Brosseau 2002), articular
structures (Cibulka 1986) and neural tissue (Turl 1998); education, including awareness of the risks for hamstring injury and
importance of training (Arnason 2005); and functional training
and sport specific drills (Verrall 2005).
Why it is important to do this review
Despite the relatively high incidence of hamstring injuries in sport,
evidence of the efficacy of preventive interventions is not well
established. The authors were not aware of any systematic reviews
specifically focused on the interventions used for the prevention
of hamstring injuries.
OBJECTIVES
To review the evidence from randomised and quasi-randomised
controlled trials evaluating interventions for preventing all types
of hamstring injuries in physically active people.
This review aimed to compare the effects (primarily the incidence
of hamstring injuries) in individuals participating in relevant sport
or physical occupations of:
1. interventions targeted at preventing hamstring injuries versus
no or placebo intervention;
Interventions for preventing hamstring injuries (Review)
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2. different targeted interventions.
We studied the outcomes in different age groups (adolescent versus
adult); by history (first time versus recurrent hamstring injury);
and participation in professional/occupational versus leisure activities.
METHODS
4. Manual therapies (articular, neural and soft tissue mobilisation
and massage);
5. Neuromuscular strategies (proprioceptive balance work);
6. Educational awareness programmes;
7. General intervention programmes (warm-up exercises, aerobic
drills).
Types of outcome measures
For inclusion, trials were required to report on the incidence of
hamstring injury.
Criteria for considering studies for this review
Primary outcomes
Types of studies
Randomised controlled trials and quasi-randomised (method of
allocating participants to a treatment which is not strictly random;
e.g. by date of birth, hospital record number, alternation) controlled trials in which any prevention approach is compared with
another or a control group. Cluster-randomised trials, abstracts
and unpublished studies where appropriate were also included.
Trials which involved testing of preventative interventions in ’laboratory’ conditions, or which only reported intermediate outcome
measures (muscle strength or flexibility) that have no proven relationship to clinical outcomes, along with reviews, were excluded.
Types of participants
We included trials involving physically active people of either sex
from adolescence (using the World Health Organization’s definition of adolescence as the period of life between 10 and 19 years
(Goodburn 1995)) to adults of any age who are at risk of incurring hamstring injuries. Participants with and without a history of
hamstring injury were included and a distinction between them
made where possible.
We excluded trials focusing on interventions for people with existing, or under treatment for, lower-limb musculoskeletal injuries.
Reports focusing on children below the age of 10 years were also
excluded.
Types of interventions
Any intervention or intervention programme (one or more intervention in comparison with a control or one or more alternative interventions) for the prevention of hamstring injuries was
included in the review.
These were categorised as:
1. Stretching or mobilising exercises;
2. Strengthening exercises (eccentric and concentric);
3. Exercise to correct movement dysfunction and sport specific
drills;
1. The incidence of any hamstring injury was included regardless of
grade, site and chronicity. Where possible, distinctions were made
between injuries that had been clinically confirmed and those that
were confirmed with imaging, and furthermore were of sufficient
severity to prevent resumption of full activities.
Secondary outcomes
1. Compliance with the intervention;
2. Severity of hamstring injuries (grade, surgery considered);
3. Complications/adverse effects associated with chosen intervention: e.g. fitness deficit, muscle soreness, other injuries;
4. Incidence of all lower-limb (leg) injuries and low back pain;
5. Measures of service utilisation or resource use (e.g. costs, diagnostic procedures).
Search methods for identification of studies
Electronic searches
We searched the Cochrane Bone, Joint and Muscle Trauma Group
Specialised Register (to December 2008), the Cochrane Central
Register of Controlled Trials (The Cochrane Library, 2008, Issue 4),
MEDLINE (1966 to December 2008), EMBASE (1980 to December 2008), CINAHL - Cumulative Index to Nursing and Allied Health Literature (1982 to December 2008), SPORTDiscus
(1949 to December 2008), AMED - The Allied and Complementary Medicine Database (1985 to July 2008), PEDro - The Physiotherapy Evidence Database (to December 2008), and reference
lists of articles. We also searched Current Controlled Trials and
the UK National Research Register (NRR) Archive (to September 2007) for ongoing and recently completed trials. No language
restrictions were applied.
In MEDLINE the search strategy was combined with the first two
sections of the optimal MEDLINE search strategy for randomised
trials (Higgins 2006) (see Appendix 1). This search strategy was
modified for use in other databases (see Appendix 1).
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Searching other resources
To identify theses and unpublished studies we contacted experts
in the field and institutions. We also checked the reference lists of
included studies and relevant systematic reviews. Furthermore we
included the findings from handsearches of supplements (1997 to
July 2008) in eight journals (Am J Sports Med; Br J Sport Med;
Sports Med; J Am Acad Orthop Surg; Chiropract Osteopathy;
Med Sci Sports Exerc; Clin J Sport Med; J Orthop Sports Phys
Ther).
individuals, for example of a football team, can not be considered
independent of the cluster unit. Statistical methods which assume
participants’ chances are independent ignore any potential similarity between outcomes for participants within the same team.
This may result in underestimated standard errors and give misleadingly narrow confidence intervals (Bland 1997). Where cluster randomisation was used, we sought the intra-cluster correlation coefficient (ICC) and pooled data using the generic inverse
variance. Exploratory analyses using assumed values for clusterrandomised studies which did not report the ICC were also included.
Data collection and analysis
Dealing with missing data
Selection of studies
Both review authors obtained and screened abstracts and citations
identified via searches. We retrieved full text articles for any that
described eligible studies. Any disagreement was resolved by discussion.
Where possible we performed intention-to-treat analyses to include all people randomised to the intervention groups. We investigated the effect of dropouts and exclusions by conducting analyses where the missing participants were assumed to have the control rate. We attempted to contact study authors where additional
information was required. If studies did not report dropouts we
assumed there were none in the analyses.
Data extraction and management
Using a data extraction form, both review authors independently
extracted trial details and data. Any differences were resolved by
discussion. Where data were not provided in the text or tables,
extraction of results from graphs in trial reports was undertaken.
Where appropriate, corresponding authors were contacted to provide missing information for trial results and methods.
Assessment of heterogeneity
Assessment of risk of bias in included studies
Assessment of reporting biases
Both review authors independently assessed the included studies using a piloted modification of the former quality assessment
tool developed by the Cochrane Bone, Joint and Muscle Trauma
Group. Each criterion is rated as either ’Y’ (Yes), ’?’ (uncertain/ unknown) or ’N’ (No), depending on how successfully the criterion
was met. The rating scheme covering 14 aspects of trial validity,
plus brief notes of coding guidelines for some items, is shown in
Table 1.
If there had been sufficient data available to assess publication bias,
we planned to prepare a funnel plot.
Measures of treatment effect
Quantitative outcome data given in individual trial reports were
presented in the text and in the analyses. For dichotomous variables, risk ratios and 95% confidence intervals were calculated.
Unit of analysis issues
The unit of randomisation in these trials may be groups of individuals, such as a football team, rather than individuals. For such trials, unit of analysis errors are likely to result from the presentation
of the outcomes for individual participants. The risk of injury in
Where appropriate, we performed a meta-analysis where studies
were sufficiently clinically homogeneous. Statistical heterogeneity
was assessed by visual inspection of the forest plot (analysis) along
with consideration of the test for heterogeneity Chi² and the I²
statistic (Higgins 2003).
Data synthesis
If studies were statistically homogeneous, we planned to use
the fixed-effect model. If studies were statistically heterogeneous,
the random-effects model was used or results were not pooled,
whichever appeared the most appropriate. RevMan was used for
statistical analyses. Where data allowed and where appropriate, we
planned to calculate ’number needed to treat’ (NNT) statistics for
prevention of hamstring injuries.
Subgroup analysis and investigation of heterogeneity
We planned to perform a subgroup analysis by therapeutic approach as outlined under Types of interventions. This included a
comparison of each approach versus control protocols, as well as
direct comparisons of different approaches. Furthermore subgroup
analysis of age (adolescents and adults), gender, history or not of
hamstring injury, occupational or leisure activity was planned. To
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test whether these subgroups were statistically significantly different from one another, we intended to test their interaction using
the technique outlined by Altman and Bland (Altman 2003).
2003; Engebretsen 2008; Gabbe 2006; Söderman 2000), Australian rules football (Hoskins 2008) and high school basketball
(Emery 2007), and recreational running in Van Mechelen 1993.
Sensitivity analysis
Participants
Where possible, we planned sensitivity analyses on the primary
outcome examining various aspects of trial and review methodology, including the effects of missing data, study quality (specifically allocation concealment and outcome assessor blinding), and
inclusion of trials only reported in abstracts or unpublished reports.
Participants were restricted to males in five studies (Askling 2003;
Engebretsen 2008; Gabbe 2006; Hoskins 2008; Van Mechelen
1993), whereas all participants were female in Söderman 2000.
Emery 2007 included similar numbers of males and females.
Emery 2007 included adolescents only (aged 12 to 18 years).
The mean ages of trial participants in five studies (Askling 2003;
Engebretsen 2008; Gabbe 2006; Hoskins 2008; Söderman 2000)
ranged from 20 to 26 years old. It is likely that the adult civil
servants in another trial (Van Mechelen 1993) formed a slightly
older population. Two studies (Askling 2003; Gabbe 2006) excluded people with any injury present at the time of recruitment,
whereas another (Emery 2007) excluded any injury within six
weeks that prevented full participation in basketball at the start of
the season. More specifically two studies (Askling 2003; Hoskins
2008) excluded people with a history of chronic hamstring injuries; however, it was not clear if this included minor as well as
major sprains. Three studies (Engebretsen 2008; Söderman 2000;
Van Mechelen 1993) failed to disclose any exclusion criteria. However, the subgroup of trial participants included in this review from
Engebretsen 2008 all had a history of an acute hamstring injury
during the previous 12 months.
RESULTS
Description of studies
See: Characteristics of included studies; Characteristics of excluded
studies.
Results of the search
Electronic and manual searching yielded 308 relevant articles of
which 285 were eliminated on inspection of the citation or reference as clearly not eligible for the review. Overall, 23 randomised
studies were retrieved from the literature searches and subsequently
evaluated. Review of the full texts led us to include seven trials and
exclude the 16 other studies for reasons given in the Characteristics
of excluded studies table. Correspondence with the author of one
study available only as an abstract (Hoskins 2006), led to the
retrieval of a full unpublished report intended for publication
(Hoskins 2008).
Included studies
Seven randomised controlled studies, six published (Askling 2003;
Emery 2007; Engebretsen 2008; Gabbe 2006; Söderman 2000;
Van Mechelen 1993), and one unpublished study (Hoskins 2008),
were included. Overall, a total of 1919 participants were included
in this review. Two trials (Emery 2007; Söderman 2000) were
cluster randomised trials where teams rather than individuals were
randomised. Details of each of the included trials are given in the
Characteristics of included studies table.
Setting
All of the prevention studies involved people, predominantly
young adults, participating in regular sporting activities. Interventions were applied in field/court sports such as football (Askling
Interventions
Four trials (Askling 2003; Engebretsen 2008; Gabbe 2006;
Hoskins 2008) tested interventions aimed directly at preventing
hamstring injuries. In Engebretsen 2008, this applied to a subgroup of 37 participants who received only interventions targeting
hamstring injury prevention. Data for this subgroup were obtained
from the trial author. The remaining three trials (Emery 2007;
Söderman 2000; Van Mechelen 1993) reported the outcomes of
interventions aimed at preventing lower limb injuries; where available data for hamstring injury occurrence was extracted. There
were four comparisons.
Three trials (Askling 2003; Engebretsen 2008; Gabbe 2006), involving 287 participants, compared the use of eccentric hamstring
strength training. Two studies (Askling 2003; Engebretsen 2008)
evaluated the effect of eccentric strength training on the non-fatigued muscle, whereas the remaining study (Gabbe 2006) evaluated the effects after core training sessions.
In Askling 2003, participants decelerated a flywheel ergometer by
eccentric hamstring action. The ergometer was set to ‘overload’
the hamstrings (‘eccentric overload training’): to produce a moving force greater than these muscles could concentrically generate or statically resist. The remaining two studies (Engebretsen
2008; Gabbe 2006) employed standard eccentric strength training
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6
(without ‘overload’) using the Nordic hamstring exercise. This is
an exercise in which the athlete kneels upright on a mat, ankles
supported by an assistant, then gradually straightens their knees
by tilting forwards and slowly lowering themselves to the floor.
When the athlete is unable to control the lowering any further,
they are able to relax, fall forward and stop their descent with their
arms.
Hoskins 2008 investigated the use of manual therapy techniques
including high velocity low amplitude (HVLA) manipulation and
mobilisation and/or supporting soft tissue therapies to prevent
hamstring injuries in 59 participants.
Two cluster randomised trials (Emery 2007; Söderman 2000),
involving 1152 participants, investigated the use of proprioceptive
neuromuscular training. Both studies incorporated the use of a
home balance-board training protocol, although in only Söderman
2000 did the difficulty of training increase, by progressing the
exercises as well as adjusting the height of the balance board.
Van Mechelen 1993, which involved 421 participants, investigated
a health education intervention aimed at injury awareness and with
accompanying instructions for appropriate activities for warm-up
before running, cool-down after running and regular stretching
exercises, with control. The stretching exercises targeted the low
back and the major lower limb muscle groups (hip/knee flexors
and extensors, hip adductors and calf muscles).
The intensity of training schedules varied in the trials. The majority of trials did not disclose exact intensity times, but six studies
(Askling 2003; Engebretsen 2008; Gabbe 2006; Hoskins 2008;
Söderman 2000) reported the number of training sessions implemented within the intervention period. These are summarised in
Table 2.
Outcomes
Primary outcome: Incidence of hamstring injuries
The methods for assessing injury diagnosis were stated in all trials. All reported the incidence of lower limb injuries by location
and by type. The primary outcome was the occurrence of hamstring injury defined by clinical physical assessment. Diagnosis was
made by medical personnel (Hoskins 2008), physical therapists
(Askling 2003; Engebretsen 2008; Gabbe 2006; Van Mechelen
1993) and orthopaedic surgeons (Söderman 2000). The definitions for injury were similar in five studies (Askling 2003; Emery
2007; Engebretsen 2008; Hoskins 2008; Söderman 2000). Injury
was defined as that which occurred during scheduled football/basketball matches or practices and caused the player to, at least, miss
the next game or practice session. Gabbe 2006 defined injury by
sudden onset posterior thigh pain, tenderness on palpation, with
or without pain on stretch of the hamstring muscles; and with
or without pain on contraction of the hamstring muscles. Lastly,
Van Mechelen 1993 defined an injury as that causing the participant to stop running, being unable to run on the next occasion,
being unable to work the next day, needing medical attention, or
suffering from pain or stiffness during 10 subsequent days while
running.
Secondary outcomes
Secondary outcomes sought were less frequently reported. Four
studies (Emery 2007; Engebretsen 2008; Gabbe 2006; Van
Mechelen 1993) disclosed information on compliance. The studies presented this information from self-reported data and presented data as percentages, although definitions of compliance differed, from participation in full protocols (Van Mechelen 1993),
participation in over 80% of training sessions (Engebretsen 2008),
participation in home training protocols (Emery 2007), to participation in more than one home-based session (Gabbe 2006). Four
studies (Askling 2003; Emery 2007; Engebretsen 2008; Söderman
2000) disclosed the severity of injury, although definitions differed
between all five. Askling 2003 defined minor injuries as up to seven
days loss from practice/matches, moderate injuries as 1 to 4 weeks,
and major injuries as 4 weeks loss from practice/matches. Emery
2007 defined minor injuries as 0 to 7 days time loss from basketball, moderate injuries as 8 to 21 days, and severe as greater than
21 days loss from basketball. Engebretsen 2008 defined minor injuries as 1 to 7 days inability to participate in football matches
or training, moderate injuries as 8 to 28 days, and severe injuries
as greater than 28 days. Söderman 2000 defined minor injuries
as absence from training/games for less than 7 days, moderate injuries as absence from 7 to 30 days, and severe injuries as absence
more than 30 days.
Three studies (Askling 2003; Gabbe 2006; Hoskins 2008) disclosed data/information on any adverse effects of the interventions delivered. In addition, five studies (Emery 2007; Engebretsen
2008; Hoskins 2008; Söderman 2000; Van Mechelen 1993) reported the injury occurrence for all lower limb injuries as dichotomous variable injury incidence. In two studies this data was obtained by personal communication with the authors (Emery 2007;
Engebretsen 2008). Hoskins 2008 recorded low back pain, using
the McGill Pain questionnaire short form. No study performed
any economic evaluation or presented measures of service utilisation or resource use.
Excluded studies
Review of the full texts led us to exclude 16 studies (Arnason 2005;
Arnason 2006; Bixler 1992; Cabry 2000; Cross 1999; Ekstrand
1983; Hägglund 2007; Hartig 1999; Heidt 2000; Larsen 2002;
Olsen 2005; Pope 2000; Rudzki 1997; Verrall 2003; Wedderkopp
1999; Withnall 2006), due to at least one of the following three
reasons: trial assessed re-injury rather than initial occurrence of
hamstring injuries; study was not a randomised controlled trial;
or study did not report hamstring injury. In some cases, correspondence with the authors confirmed exclusion: raw data were
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
7
either unavailable or anatomical recording was insufficient to differentiate between a hamstring injury and other types of thigh
injury. Some details of the 16 excluded trials are provided in the
Characteristics of excluded studies table.
Risk of bias in included studies
In this review, risk of bias was assessed indirectly in terms of different aspects of methodological quality (see Table 1).
Overall the methodological quality of the seven included papers
was only poor to moderate, reflecting inadequate allocation concealment, lack of blinding and incomplete outcome data. Table 3
shows the results of the methodological quality assessment of the
individual trials.
In the following we report on items relating to randomisation, allocation concealment, assessor blinding, completeness of followup and care programme comparability. Details of these for individual trials are presented in Methods of the Characteristics of
included studies table.
2007, after allocation of the participating schools to one of two
interventions, coaches of eight of the 105 teams within the 25
participating schools declined participation. The loss to followup from this was not reported. In two studies (Söderman 2000;
Van Mechelen 1993), 37% and 23% respectively of randomised
participants were lost to follow-up. Intention-to-treat analysis was
presented in two studies (Engebretsen 2008; Gabbe 2006).
Other potential sources of bias
Although participants were part of teams in most circumstances,
which would to some degree impose some reliability, generally
there was insufficient information concerning the equivalence of
the so called ’care programmes’ (consisting of other preventative
measures such as stretching components, manipulative physical
therapy, massage, strengthening exercises and conditioning). As
a result, further active measures for prevention of hamstring injuries could have been employed preferentially in one group rather
than another, therefore potentially introducing performance bias.
Four trials (Askling 2003; Engebretsen 2008; Emery 2007; Gabbe
2006) provided sufficient information of comparability.
Allocation
Four (Emery 2007; Engebretsen 2008; Gabbe 2006; Hoskins
2008) of the seven studies provided sufficient details of the method
of randomisation. Two studies (Gabbe 2006; Hoskins 2008) stratified eligible players by age and hamstring injury history and allocated them using a computer generated randomisation list. Emery
2007 and Engebretsen 2008 used computer generation of random numbers. Teams or groups of people (cluster randomised)
rather than individuals were randomised in two trials (Emery
2007: schools; Söderman 2000: soccer teams). Only Emery 2007
considered the associated unit of analysis problems and provided
an intracluster correlation coefficient.
Only two studies (Emery 2007; Hoskins 2008) had adequate allocation concealment. Hoskins 2008 explicitly stated that allocation
was concealed. There was insufficient information to judge this
item for the remaining five studies.
Blinding
Four studies reported assessor blinding (Askling 2003; Emery
2007; Gabbe 2006; Hoskins 2008), but this seemed assured in
only two of these (Emery 2007; Hoskins 2008). Emery 2007
also reported intervention provider blinding to assignment status.
The nature of some interventions (e.g. manual therapy) precluded
blinding of participants or providers.
Incomplete outcome data
Loss to follow-up including post-randomisation exclusions were
reported in four trials (Emery 2007; Hoskins 2008; Söderman
2000; Van Mechelen 1993) and were generally large. In Emery
Effects of interventions
The four comparisons are reported in turn below. Intention-totreat analysis was performed wherever possible. No study reported
cost data or gave any economic evaluation.
Strengthening protocol for hamstring muscle group
versus control
Three trials (Askling 2003; Engebretsen 2008; Gabbe 2006) tested
strength training for the hamstring musculature. Pooled results,
done on an exploratory basis, for participants sustaining hamstring
injuries showed substantial heterogeneity between the results of
three trials (I² = 62%) and no statistically significant difference
between the two groups (risk ratio (RR) 0.83, 95% confidence
interval (CI) 0.26 to 2.65; random-effects; see Analysis 1.1). Only
a portion of study participants of Askling 2003 (33%) and Gabbe
2006 (14%) had a past history of hamstring injury, thus predisposing them to high possibility of injury recurrence (Orchard 2002b).
In contrast, all of the subgroup of participants from Engebretsen
2008 were selected solely due to their high risk of hamstring injury, primarily due to past history.
Only Askling 2003 reported data on the severity of hamstring
injuries, based on duration of absence from practice or matches.
Most of the injuries were minor in that they caused absence from
test matches for under a week. There were no statistically significant differences between the two groups in the number of participants with more serious injuries (2/15 versus 3/15, RR 0.67, 95%
CI 0.13 to 3.44; see Analysis 1.2).
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8
Reported compliance with the intervention was poor in the two
trials reporting this outcome (Engebretsen 2008; Gabbe 2006). In
Gabbe 2006, 30% of players who agreed to participate in the study
failed to complete even one of the five prescribed sessions, and
only 47% completed at least two sessions: the difference between
two groups in the participants sustaining hamstring injury was
not statistically significant (2/50 versus 7/53, RR 0.30, 95% CI
0.07 to 1.39; see Analysis 1.2). None of the 24 participants in
Engebretsen 2008 prescribed strength training were classified as
compliant (20 sessions or more).
Only Engebretsen 2008 provided data on overall lower limb injuries. There was no statistically significant difference between the
two groups in the number of participants sustaining a lower limb
injury (RR 0.84, 95% CI 0.51 to 1.38; see Analysis 1.3).
Adverse event data were incompletely reported. Eccentric strength
training (Askling 2003; Gabbe 2006) reportedly resulted in delayed onset muscle soreness (DOMS). Although this type of soreness is a response of the muscle to the damage induced by eccentric
exercise, DOMS is believed to have a protective effect against further injury. However, in Gabbe 2006 the DOMS experienced inhibited the players’ ability to participate in subsequent club training sessions and, in addition, players believed that the soreness
would increase their risk of hamstring injury which reduced compliance. In Askling 2003, 11 players out of 15 had subjectively
reported they had experienced muscle soreness of varying intensity
1 to 3 days after training, although this did not seem to affect their
continued participation and attitudes towards the intervention.
Manual therapy protocol versus control
Hoskins 2008 evaluated manual therapy for preventing hamstring
injuries. Though fewer participants sustained a hamstring injury
in the intervention group, the difference between the two groups
was not statistically significant (1/28 versus 5/29, RR 0.21, 95%
CI 0.03 to 1.66; see Analysis 2.1). Two of the five control group
participants sustaining a hamstring injury went on to incur a second hamstring injury.
Hoskins 2008 found that fewer participants sustained lower limb
injuries in the manual therapy group. This finding was statistically
significant for lower limb muscle strain (RR 0.13, 95% CI 0.02
to 0.97; see Analysis 2.2) but not for non-contact knee injury (RR
0.15, 95% CI 0.02 to 1.13; see Analysis 2.2). Hoskins reported “A
positive statistical change for the intervention group was achieved
for overall and current LBP [low back pain]”, as assessed using the
McGill Pain Questionnaire (short form).
Hoskins 2008 reported that no players reported an adverse reaction
to manual therapy.
Proprioceptive training protocol versus control
Two cluster randomised trials (Emery 2007; Söderman 2000)
tested proprioceptive neuromuscular training. Emery 2007 provided an intra-cluster correlation coefficient (ICC = 0.006). We
considered that it was reasonable to use the same ICC to correct for
clustering for Söderman 2000. However, both trials had problems
with loss to follow-up, and moreover, Söderman 2000 reported
number of injuries rather than participants incurring injuries. All
the analyses presented here are exploratory.
Uncorrected data for hamstring injuries for the two trials are
presented in Analysis 3.1. As well as a large loss to follow-up
in Söderman 2000, the results for 27 non-compliant intervention group participants were not available. The second analysis
in Analysis 3.1 is an intention-to-treat analysis where the missing
participants (these were just from the one dropped-out enrolled
team in Emery 2007) are assumed to have the same incidence of
injury as the control rate. Neither analysis shows a statistically significant difference between the intervention and control groups in
hamstring injury for either trial. Analysis 3.2 presents the ’intention-to-treat’ analysis corrected for clustering. Again, this shows
the lack of statistically significant differences for both trials (Emery
2007: RR 0.28, 95% CI 0.02 to 3.35; Söderman 2000: RR 0.53,
95% CI 0.17 to 1.63). Neither trial provided information on the
severity of the hamstring injuries.
Uncorrected data for all lower limb injuries for the two trials are
presented in Analysis 3.3. The second analysis in Analysis 3.3 is
an intention-to-treat analysis where the missing participants are
assumed to have same incidence of injury as the control rate. Neither analysis shows a statistically significant difference between the
intervention and control groups in overall lower-limb injuries for
either trial. Analysis 3.4 presents the ’intention-to-treat’ analysis
corrected for clustering. This once more confirms the lack of statistically significant differences for both trials (Emery 2007: RR
0.80, 95% CI 0.60 to 1.06; Söderman 2000: RR 1.05, 95% CI
0.75 to 1.46).
It was unclear whether any adverse events occurred in either trial.
For Emery 2007, self-reported compliance data were only returned
by 73.3% of players and this showed that only 60.3% of these
had participated in the home-based proprioceptive training beyond the designated team warm-up activities. Within the 60.3%
of participants, the median score of home-based sessions was 9 out
of a possible 43 sessions.
Warm-up, cool down and stretching protocol versus
control (Comparison 4)
One study (Van Mechelen 1993) evaluated the effectiveness of
stretching interventions alongside warm-up/cool down protocols
on the prevention of injuries at the end of the 16-week treatment
period. As well as a 23% loss to follow-up, location-specific injury
data were only available for 44 out of 49 injuries. There were three
hamstring injuries (“posterior side upper leg”) in each group (RR
1.05, 95% CI 0.22 to 5.13; see Analysis 4.1). Of the 44 injuries,
one located in the lower back was registered for the intervention
group. There was no significant difference between the two groups
in the numbers of recorded lower limb injuries (RR 1.21, 95% CI
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
9
0.69 to 2.11; see Analysis 4.2). It is not known whether the trial
participants sustained more than one injury.
In Van Mechelen 1993, compliance was assessed by analysing participants’ self-reported daily diaries to determine if performance
of the exercises was in accordance with those prescribed. It was
found that 46.6% (74/159) in the intervention group and 4.8%
(8/167) in the control group performed stretching exercises to the
prescribed intervention.
Subgroup analysis
Direct comparisons of different interventions were not conducted
within randomised trials. Furthermore, it was not possible to perform subgroup analysis for age (adolescents and adults), gender or
history of hamstring injury due to insufficient data.
DISCUSSION
Hamstring injuries are highly prevalent, and result in the need
for medical care, missed competition, work, or habitual activities.
Reductions in the incidence or severity of these events have the
potential to reduce medical costs, lost time from work or leisure,
and suffering. This review paper examines the evidence for interventions to prevent hamstring injuries from the clinical trials literature using a systematic approach. At present very little empirical
evidence exists to support the efficacy of prevention regimens
20.79). Reported compliance was poor in both Engebretsen 2008
and Gabbe 2006. While muscle soreness was reported for intervention group participants in both Askling 2003 and Gabbe 2006,
this seemed only to affect compliance and participation in Gabbe
2006.
One underpowered trial (Hoskins 2008) found some evidence for
a potential protective effect from manual therapy but the difference
for hamstring injury was not statistically significant (RR 0.21,
95% CI 0.03 to 1.66). However, there was a statistically significant
difference in favour of the manual therapy group for lower-limb
muscle strain (RR 0.13, 95% 0.02 to 0.97), and back pain. No
adverse effects of manual therapy were recorded.
The remaining three trials tested interventions for preventing
lower-limb injuries rather than directly targeting hamstring injury.
Proprioceptive training for prevention of lower-limb injuries was
evaluated by two cluster randomised trials. Exploratory analyses
with ’intention-to-treat’ analysis corrected for clustering showed
a lack of statistically significant differences between the intervention and control groups in hamstring injury for both trials. Notably, only four participants incurred hamstring injury in Emery
2007. Only data for hamstring injuries rather than participants
sustaining a hamstring injury were available for Söderman 2000.
Equal numbers of participants sustained hamstring injuries in the
intervention and control group of Van Mechelen 1993, which
evaluated stretching alongside warm-up/cool down protocols (RR
1.05, 95% CI 0.22 to 5.13). As well as recording low compliance,
Van Mechelen 1993 also had substantial loss to follow-up.
Summary of main results
Overall completeness and applicability of
evidence
Seven randomised controlled studies, involving a total of 1919
participants, were included. These evaluated four different interventions: hamstring muscle group strengthening; manual therapy; proprioceptive training and a warm-up/ cool down/ stretching protocol. The trials were heterogeneous but all involved active people, predominantly young adults, participating in regular
sporting activities.
Where possible intention-to-treat analyses including all trial participants for participants sustaining at hamstring injuries were presented. All results had wide confidence intervals.
Pooled data from three heterogeneous trials testing strengthening
protocols for hamstrings showed no statistically significant difference between intervention and control groups in the incidence
of participants sustaining a hamstring injury (random effects: RR
0.83, 95% CI 0.26 to 2.65; I² = 62%). Although Askling 2003
found a significant benefit for strengthening (RR 0.30, 95% 0.10
to 0.88), the control rate of mainly minor hamstring injury was
unusually high (67%). When data from all participants in Gabbe
2006 were included there was no evidence of a benefit (RR 1.16,
95% 0.48 to 2.83). Engebretsen 2008 also found no evidence of
benefit for hamstring strengthening (RR 2.71; 95% CI 0.35 to
The applicability of the results from this review are strengthened
by the fact that the included studies incorporated sportsmen and
women across a number of sporting domains. Furthermore the
small between-group differences in definitions of injury for surveillance systems in team sports indicates a reliable and valid approach
to injury rates within these studies and supports recommendations
that “a match time loss definition” should form the basis for the
injury definition in a consensus statement (Orchard 2007).
Four of the included trials tested interventions specifically targeted
at preventing hamstring injuries. Three of these trials with 287
participants evaluated strengthening protocols and one with 59
participants evaluated manual therapy.
Insufficient data and the statistical heterogeneity of the pooled data
for strengthening protocols hampers the drawing of conclusions
on effect and hence applicability. As indicated above, the control
rate of hamstring injury in Askling 2003 is unusually high but
may, as discussed by Askling 2003, reflect their data collection
method. The favourable findings of Askling 2003 were not found
in Engebretsen 2008 nor Gabbe 2006. While subgroup analysis
including compliers only (completion of at least two of the five
sessions) in Gabbe 2006 seemed to point to a potential but not
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
10
statistically significant benefit from strengthening, the validity of
this finding is questionable given that the results for non-compliers
favoured the control group. It is notable that all of the subgroup
of participants from Engebretsen 2008 were selected solely due to
their high risk of hamstring injury, primarily due to past history
thus predisposing them to high possibility of injury recurrence (
Orchard 2002b). It is, however, not possible to determine from the
available data whether past history of hamstring injury affects the
potential for strengthening to prevent hamstring injuries. Askling
2003 involved the use of specific equipment, which limits the
applicability of this trial to situations where there are sufficient
resources.
Although the trial testing manual therapy did not find a statistically
significant result for hamstring injury, the statistically significant
reduction in lower limb muscle strain and back strain points to
a promising intervention. This is strengthened by the fact that
Hoskins 2008 exhibits strong external validity in reference to the
active population in question.
The remaining three trials (Emery 2007; Söderman 2000; Van
Mechelen 1993) reported the outcomes of interventions for the
prevention of leg injuries, including providing data for hamstring
injuries. We excluded several other trials that did not provide data
on hamstring injuries but were otherwise suitable for inclusion.
The results for the above three trials thus must be put in the context
of the missing data from these excluded trials.
In terms of preventing hamstring injuries, the clinical applicability
of the results of the two trials (Emery 2007; Söderman 2000) testing proprioceptive protocols (involving wobble board exercises)
is uncertain. Although analytical findings for proprioceptive protocols demonstrate potentially small protective effects, both included studies (Emery 2007; Söderman 2000) targeted the prevention of leg injuries rather than hamstring injuries in isolation.
Therefore its true protective effect on hamstring injury prevention remains in doubt. Doubts over applicability are further compounded by the fact that interventions were tested on adolescents
in one study (Emery 2007). As noted already, injury frequency and
severity to adolescents differs from that in adults (Frank 2007).
However, there were only four hamstring injuries in Emery 2007.
It is possible that this may reflect that control group participants
were given dynamic stretch components. Dynamic stretches tend
to incorporate more sport specific movements. This may have resulted in a training effect on the neuromuscular system promoting neuromuscular control and thus reducing injury occurrence
(Mandelbaum 2005), therefore resulting in similar training effects
to proprioceptive interventions.
The ineffectiveness of warm-up/ cool down/ stretching protocols
(Van Mechelen 1993) in preventing of hamstring injuries may
reflect the more generalised approach to lower limb injury and
poor compliance with stretching exercises. It may also result from
an inadequate intervention. In Van Mechelen 1993, stretching
exercises were held for only 10 seconds, whereas current evidence
suggests that stretches need to be held for at least 20 seconds to
influence the stretch reflex and allow for elongation of muscle
fibres (Bandy 1997).
The occurrence of adverse events in some of the trials may influence their true clinical applicability. A reduction in joint range of
motion, peak torque, along with alterations in muscle sequencing and recruitment patterns has been associated with DOMS
(Cheung 2003). Nonetheless, the effect of DOMS on overall
sporting performance has not been well documented. Stretching
also has its potential harms, associated with a temporary strength
deficit hindering performance (Kokkonen 1998). The side-effects
of manual therapy have also been investigated. Common reactions
include local discomfort, headache, fatigue and radiating discomfort (Senstad 1996); however, these are usually benign in nature
and of short duration. Potential harms may greatly influence consent, compliance and the overall selection of an intervention, especially in a sporting domain, and therefore there is a need for
specifically focused research to investigate adverse events within
hamstring prevention protocols.
Several studies reported poor compliance with the chosen interventions, sometimes further compounded by adverse events (as in
Gabbe 2006), although these events were minor. The ability of a
participant to adhere to the prevention protocol is without doubt
an important factor to be considered when applying this intervention in clinical practice, potentially having an impact on compliance and thus hamstring injury prevention within a sporting
or recreational setting and within any future studies in this field.
In addition, the large between-group differences in definitions of
injury severity suggest that there is a need for a better consensus.
This is an important factor to consider when assessing the true
efficacy of interventions in preventing different grades of severity
of hamstring injuries within a clinical setting.
Finally, it should be noted that all included studies failed to exclude
injuries sustained through direct contact. Various sports include
physical contact and it has been proposed that there is a direct relationship between the amount of contact a player gives or receives
and the incidence of injury (Mueller 1996). Masking of the true
efficacy of an intervention may arise if injuries occurring by such
mechanisms are included.
Quality of the evidence
We included only randomised and quasi-randomised controlled
trials as they are less susceptible to selection bias (Roberts 1998).
However, it was unclear whether selection bias had been avoided in
most of the included trials and there was risk of bias also from lack
of blinding and incomplete outcome data. Given this potential for
bias, results from these trials should be interpreted with caution.
In two studies (Söderman 2000; Van Mechelen 1993), over 20% of
randomised participants were lost to follow-up. Research suggests
that greater than 20% loss potentially poses serious threats to validity, and in-between levels lead to intermediate levels of problems
(Sackett 1997). The problem was compounded in Söderman 2000
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Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
11
through the exclusion of intervention group participants who had
not complied. In Emery 2007, after allocation of the participating
schools to one of two interventions, coaches of eight of the 105
teams within the 25 participating schools declined participation.
The loss to follow-up from this was not reported. Intention-totreat analysis was, however, possible for four trials (Askling 2003;
Engebretsen 2008; Gabbe 2006, Hoskins 2008).
Interpretation of the results of small studies may be compromised
by the lack of power. Hamstring occurrence among a healthy active population is a relatively small occurrence. The sample sizes
used by the trials were insufficient to account for a relatively small
occurrence of injury within a healthy population. For example,
Hoskins 2008 failed to demonstrate a statistically significant difference between groups in hamstring injury, but with only 59 participants it is difficult to determine whether this finding was due to
inadequate power or the lack of effect. All findings in this review
were associated with wide confidence intervals, which hampers the
interpretation of the clinical significance.
Lack of participant blinding to group allocation is potentially important in these trials. Knowledge of group assignment can affect
responses to the intervention received and introduce performance
bias (Schulz 2002). Participants who know that they have been assigned to a group who will receive a new treatment might harbour
favourable expectations (Hawthorn Effect) or increased apprehension. Futhermore a lack of treatment provider blinding may have
introduced detection bias, whereby the assessors are likely to have
preferentially attributed injury occurrence to the control group.
However, it is important to consider that it would be difficult to
blind participants and providers in competitive sporting domains.
Sports clubs may be very reluctant to engage in research studies
that possess control groups with no intervention, potentially placing participants at greater risk of injury. To accommodate this,
modern research design often requires new interventions to be
compared with the existing best practice approach. This pragmatic
research design makes it very difficult to achieve participant and
provider blinding.
Finally due to the presence of a pragmatic research design in all
seven included studies, the presence of a combination of interventions to prevent hamstring injury may explain the observed effects. Application of combined interventions in an environmental
context is a more realistic approach to prevention of injury. Rarely
is it the case that one aetiological factor is the cause of injury, factors may be multiple and interact (Croisier 2004). Nevertheless,
it may be difficult to attribute the significance of the observed
effects solely to the intervention type being investigated because
of the presence of combined intervention protocols and thus the
inclusion of such a factor may mask the true efficacy of the interventions being tested.
We are confident that we were exhaustive in our search strategy.
In an effort to locate all relevant trials, sensitive searches were conducted across a comprehensive list of electronic databases. To identify grey literature, we performed citation tracking and searched
for unpublished studies through internet clinical trials registers.
However, it is still possible that we missed some trials, especially
trials evaluating interventions for preventing lower-limb injuries
for which separate hamstring injuries data were perhaps available
but not evidently so in the electronic citation and abstract.
Despite our efforts and often success in contacting authors, this
review is limited by the availability of data from the studies.
Eleven studies meeting the inclusion criteria were excluded primarily because of lack of data on hamstring injuries (Arnason 2005;
Bixler 1992; Cabry 2000; Ekstrand 1983; Hartig 1999; Larsen
2002; Olsen 2005; Pope 2000; Rudzki 1997; Wedderkopp 1999;
Withnall 2006). Most of these trials tested interventions aimed at
preventing leg injuries rather than specifically targeting hamstring
injury. The probable extent of missing data limits the conclusions
that we can draw from the three trials in this category for which
hamstring injury data were available.
Agreements and disagreements with other
studies or reviews
A recent systematic review on the rehabilitation of hamstring injuries (Mason 2007) called for consideration of the lumbar spine,
sacroiliac and pelvic orientation and control mechanisms when
diagnosing and managing the rehabilitation of hamstring injuries.
The results from Hoskins 2008 are compatible with these recommendations in that manual therapy applied to the spine and pelvis
reduced the rate of hamstring injury.
Our finding for strengthening protocols was inconclusive. However, the choice of eccentric hamstring strength training by the
three trials testing strengthening protocols rather than concentric
strengthening is supported by the findings of a randomised trial
comparing eccentric versus concentric hamstring strengthening
(Mjølsnes 2004).
The results presented for stretching protocols are in agreement
with two existing systematic reviews (Thacker 2004; Weldon
2003), which concluded that no definitive conclusions could be
drawn as to the value of stretching for reducing the risk of injury.
AUTHORS’ CONCLUSIONS
Implications for practice
Potential biases in the review process
There is insufficient evidence from randomised controlled trials
to draw conclusions on the effectiveness of interventions used to
prevent hamstring injuries in people participating in football or
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
12
other high risk activities for these injuries. The promising findings
for manual therapy need confirmation.
Implications for research
Rigorously conducted and sufficiently powered randomised controlled trials are warranted to determine the effects of commonly used interventions, particularly stretching, strengthening
and manual therapy protocols, that target the prevention of
hamstring injuries. Trials evaluating interventions for preventing
lower-limb injuries overall should record and report on specific injuries, including hamstring injuries, and also present injury data by
participants. There remains a need for well-conducted randomised
controlled trials to justify the continued inclusion of stretching
protocols within prevention programmes. Where randomisation
by clusters seems valid, appropriate analyses of outcome and the
inclusion of sufficient information in trial reports to aid interpretation by readers and users should be undertaken (Campbell 2004).
Research should also be considered on upcoming and relatively
neglected areas. These include the encouraging role of health education, particularly in terms of injury awareness and running
technique in hamstring injury. (A common mechanism of injury
occurs through poor running technique, resulting in over-striding
(Orchard 2002b).) Reflecting the complex interactions of intrinsic and extrinsic risk factors for hamstring injury in individuals,
consideration of research on multi-modal approaches, probably
tailored towards individuals addressing more than one risk factor,
for prevention of injuries is warranted. The shift in current practice away from training the hamstrings through static and isolated
movements to dynamic movements, such as sports-specific drills
and plyometric exercises, should also be noted when considering
future research.
Finally, the strength of the included studies in this review was limited by a lack of compliance; future studies need to implement
techniques that will ensure that a greater number of participants
comply with interventions. Biofeedback is a technique where information regarding “hidden” physiological processes is displayed
in a form understandable to the participant (Krebs 1990). This
technique has been shown to improve compliance towards exercise (Berghmans 1996), whereby participants are more easily able
to recognise the significance of an intervention throughout a trial
and can therefore reinforce compliance.
ACKNOWLEDGEMENTS
The authors would like to thank the following for helpful editorial
comments during the protocol and review stages: Nigel Hanchard,
Peter Herbison, Janet Wale and Gisela Sole. Thanks too to Joanne
Elliott for her guidance in developing the search strategies. The
authors would like to extend a special thank you to Helen Handoll
and Lindsey Elstub for their continued editorial comments and
guidance, and lastly Dee Drummond for her advice and support.
REFERENCES
References to studies included in this review
Askling 2003 {published data only}
Askling C, Karlsson J, Thorstensson A. Hamstring injury
occurrence in elite soccer players after preseason strength
training with eccentric overload. Scandinavian Journal
of Medicine & Science in Sports 2003;13(4):244–50.
[MEDLINE: 12859607]
Emery 2007 {published and unpublished data}
Emery, CA. personal communication February 9 2009.
∗
Emery CA, Rose MS, McAllister JR, Meeuwisse WH.
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Engebretsen AH. personal communication August 20 2008.
∗
Engebretsen AH, Myklebust G, Holme I, Engebretsen
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∗
Gabbe BJ, Branson R, Bennell, KL. A pilot randomised
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Hoskins W. personal communication February 7 2008.
∗
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13
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∗
Indicates the major publication for the study
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
17
CHARACTERISTICS OF STUDIES
Characteristics of included studies [ordered by study ID]
Askling 2003
Methods
Randomisation: No description of method
Loss to follow-up: Hamstring injury outcome = 0; Strength outcome = 4 (2 in control group, 2 in intervention
group); Speed outcome = 2 (1 in control group, 1 in intervention group)
Intention-to-treat analysis: No
Blinding of outcome assessors: Unknown
Blinding of participants: No
Participants
Location: Sweden, premier league top two teams
Population: 30 male soccer players (mean ages 24-26) undergoing 10 weeks of training (16 sessions)
Period of study: January 7th - November 15th (year unknown)
Inclusion: Team members of all ages
Exclusion: Goalkeepers, injured players, players with chronic hamstring problems
Interventions
Intervention group (N = 15): Additional specific hamstring training consisting of bilateral knee flexor actions
in prone, accelerating flywheel by concentric hamstring action and then decelerating with eccentric action. The
hamstring training was performed in a non-fatigued state, after a standardised warm-up period (15 minutes jogging/
cycling)
Control group (N = 15): No intervention; usual training.
Outcomes
1. Incidence of hamstring injury defined by clinical physical assessment by medical personnel (occurring during
scheduled matches or practices and causing the player to miss at least the next game or practice session)
2. Severity: minor injuries (0 to 7 days lost from practice/matches); moderate injuries (1 to 4 weeks lost); and major
injuries (> 4 weeks lost)
3. Isokinetic hamstring muscle strength (peak torque concentric and eccentric)
4. Maximal running speed (seconds)
Notes
Emery 2007
Methods
Randomisation: Cluster randomised by school using computer generated random numbers
Loss to follow up: 11 (all in the intervention group, within 1 team)
Intention-to-treat analysis: No
Blinding of outcome assessors: Yes
Blinding of participants: Unknown
Participants
Location: Calgary and the surrounding area (Canada). 25 area high schools and their basketball teams
Population: 920 high school basketball players (89 basketball teams) (age 12-18) undergoing 18 weeks
of training
Period of study: November 04 - November 05
Inclusion: Adolescents who were enrolled in a high school in Calgary and who were members of their
respective basketball team - junior/senior/male/female
Exclusion: Injury within 6 weeks that prevented full participation in basketball at the start of the basketball
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
18
Emery 2007
(Continued)
season, a history of systemic disease, neurologic disorder
Interventions
Intervention group (N = 505): Warm-up routine and in addition 5 minutes sport specific balance training
for practice sessions - approx 5 times a week, and 20 minutes home exercise programme using wobble
board (frequency not disclosed)
Control group (N = 426): Warm-up routine - 10 min warm up included aerobic, static stretch and
dynamic stretch components
Outcomes
1. Incidence of injury defined by therapist assessment (occurring during basketball resulting in medical
attention beyond team therapist and/or inability to complete current session and/or participate in next
basketball game or practice)
2. Number of injuries/1000 hrs
3. Severity: minor injuries (0 to 7 days lost from game or practice); moderate injuries (8 to 21 days lost);
and severe injuries (> 21 days lost)
4. Participation exposure (hours recorded by team manager)
5. Compliance (measured by self-reported compliance, diaries were provided)
Notes
Data were obtained through personal communication with the primary author for the numbers of participants sustaining hamstring (1 versus 3) and lower limb injuries (89 versus 96)
Risk of bias
Item
Authors’ judgement
Allocation concealment?
Yes
Description
Engebretsen 2008
Methods
Randomisation: Computer generated randomisation method
Loss to follow up: None
Intention to treat analysis: Not possible
Blinding of outcome assessors: No
Blinding of participants: No
Participants
Location: Oslo, Norway. Teams located in the proximity of Oslo and playing in the first or second division or at the
top of the third’
Population: 161 professional football players drawn from 31 teams (age unknown) undergoing 10 weeks of training
(24 sessions) in addition to one session per week for the entire football season. Only 37 of these participants were
included in this review. These participants were the only group deemed to be at high risk of developing a hamstring
injury and thus received interventions solely to prevent this type of injury. All other participants were deemed at risk
of developing other injuries and thus received combinations of interventions
Period of study: 2004 football season (period unknown)
Inclusion: The criteria for classifying players as having an assumed increased risk of injury were, a history of an acute
injury to the ankle, knee, hamstring or groin during the previous 12 months or a reduced function with an average
score of less than 80% for any of the body parts mentioned. A player fulfilling any of the inclusion criteria for any
of the 4 body parts was assigned to the high risk group
Exclusion: Not stated
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
19
Engebretsen 2008
(Continued)
Interventions
Intervention group (N = 24): 10 week preseason progression of Nordic hamstring eccentric strength training,
performed by standing on the knees on a soft foundation, slowly lowering the body toward the ground using the
hamstrings while the feet are held by a partner. Progression is achieved by increasing the initial speed, and eventually
having a partner push forward. Week 1: 2 sets of 4 repetitions; Week 2: 2 sets of 6 repetitions; Week 3: 6 sets of 6 to
8 repetitions; Week 4: 3 sets of 8 of 10 repetitions; Weeks 5-10: 3 sets of 12, 10 and 8 repetitions respectively. The
intervention players were also asked to perform the exercises once per week for the rest of the season as maintenance
Control group (N = 13): Undertook the teams’ normal preseason training regimens, otherwise no intervention
Outcomes
1. Incidence of injury defined by physiotherapist assessment (any physical complaint sustained by a player that
resulted from a soccer match or soccer training, resulting in a player being unable to take a full part in future soccer
training or match play)
2. Number of injuries/1000 hrs
3. Severity: minor injuries (1 to 7 days lost from match or training); moderate injuries (8 to 28 days lost); and major
injuries (> 28 days lost)
4. Participation exposure (match exposure defined as play between teams from different clubs, while training exposure
was defined as team-based and individual physical activities under the control or guidance of the team coaching or
fitness staff aimed at maintaining or improving soccer skills or physical condition)
5. Compliance (measured by self-reported compliance assessment forms provided)
Notes
Unpublished data for players identified to be at high risk of acquiring hamstring injuries only were obtained from
the trial author. Of the 24 players who were solely at risk of developing a hamstring injury in the intervention group,
5 sustained a hamstring injury and 14 a lower limb injury. Of 13 in the control group that were solely at risk of
developing a hamstring injury, 1 sustained a hamstring injury and 9 a lower limb injury
Gabbe 2006
Methods
Randomisation: Players were stratified by past history of a hamstring strain and then randomised according to a
computer-generated randomisation list for each club. This included blocking in groups of four or six with the order
of allocation varying within each block. Players were separated into previously injured or non-injured groups and
names entered into the randomisation spreadsheet list
Loss to follow up: 0 (but 121 (64 in the intervention group, 53 in the control group) excluded from primary analysis
that included only those who had attended at least 2 sessions)
Intention to treat analysis: Yes
Blinding of outcome assessors: Unknown
Blinding of participants: No
Participants
Location: Australia. Community level of Australian Football players from seven amateur clubs
Population: 220 players from seven amateur clubs (age 17-36) undergoing 12 weeks of training
Period of study: 2004
Inclusion criteria: Team members of all ages - eligible if they would be playing in either the senior or reserve teams
during the 2004 season regardless of previous history of hamstring injury or age
Exclusion criteria: Players who were injured at the time of recruitment
Interventions
Intervention (N = 114): Additional eccentric exercise programme, one exercise performed as 12 sets of six repetitions
with 10 seconds rest between repetitions and rest periods of 2 to 3 minutes between sets, over a five-session program
within a12-week period
Control group (N = 106): The control group program involved a group of stretching and range of movement
exercise of equivalent duration to the intervention group’s programme. The exercises included were: 1. gastrocnemius
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
20
Gabbe 2006
(Continued)
stretch performed in standing; 2. hip flexor stretch performed in kneeling; 3. hamstring stretch performed in supine
(also called the active knee extension or “90/90”stretch); 4. hamstring stretch performed in sitting; and 5. lumbar
spine rotation performed in supine. Each of these exercises was performed three times on each side as a static stretch
held for 30 seconds. The exception to this was the lumbar spine rotation which was held for 15 seconds only
Outcomes
1. Incidence of hamstring injury defined by club physiotherapist assessment (i. sudden onset posterior thigh pain; ii.
tenderness on palpation; iii. with or without pain on stretch of the hamstring muscles; and iv. with or without pain
on contraction of the hamstring muscles)
2. Compliance
Notes
Clarification received from author of results for players within the ’compliant subgroup’ who completed two or more
sessions
Hoskins 2008
Methods
Randomisation: After completion of a baseline questionnaire players were then randomly allocated into
one of two groups such that allocation was concealed Eligible players were stratified by age and hamstring
injury history and allocated using a computer generated randomisation list for each club within these
strata. Players were then finally allocated to either the intervention or control with a coin toss
Loss to follow up: 1 in the intervention group and 1 in the control group
Intention to treat analysis: No
Blinding of outcome assessors: Yes
Blinding of participants: No
Participants
Location: Australian. Semi-elite state based Victorian Football League (VFL)
Population: 59 Australian rules football players recruited (4 clubs) (age 18-27) undergoing 30 weeks of
training (15 sessions)
Period of study: 2005 season (period unknown)
Inclusion criteria: Players were eligible to participate if they were listed players on their respective VFL
squad and excluded under the criteria listed
Exclusion criteria: “Red flag” conditions including: fractures, infections, inflammatory diseases, tumours
and other destructive lesions of the spine. “Yellow flag” conditions including: insurance claims, litigation;
history of malignant disease. Clinical signs suggesting inguinal or femoral hernia. Vascular disease. History
of motor vehicle accident, or other serious accident or fall in the last three months. Neurological signs
and symptoms (muscle wasting, nerve root signs, bowel, bladder or sexual dysfunction). Organic kidney,
urinary tract or reproductive disease. Recent spinal surgery (less than 2 years). Club doctor or medical
staff excluded the player’s participation. Players who had a severe history of chronic hamstring problems.
Players who had a serious injury or who had undergone surgery preventing play for the remainder of the
season
Interventions
Intervention group (N = 29): Treatment was pragmatically determined and could involve high velocity
low amplitude (HVLA) manipulation (either manual or mechanically assisted techniques), mobilization
and/or supporting soft tissue therapies, various stretching and soft tissue massage techniques to the spine,
pelvis and extremity. Treatment scheduling was also pragmatically determined
Control group (N = 30): Both the intervention and control group continued to receive the standard
club medical, paramedical and sports science management including medication, manipulative physical
therapy, massage, strengthening and conditioning and rehabilitation as directed by club staff
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
21
Hoskins 2008
(Continued)
Outcomes
1. Incidence of hamstring injury defined by club medical staff using either clinical features of injury (any
physical or medical condition that prevents a player from participating in a regular season (home and
away) or finals match), advanced imaging or both at their discretion
2. Incidence of lower limb injury
3. Adverse outcomes of intervention (defined as any undue pain, discomfort or disability arising during,
immediately after or subsequent to chiropractic therapy that resulted in missed participation in a match or
training session, required additional medical consultation or treatment or was acknowledged by a player
as not reasonably being associated or expected with the normal course of treatment). Measured by the
McGill Pain Questionnaire-SF and Health Status Questionnaire SF-39
4. Re-measure of baseline variables
Notes
The unpublished manuscript was obtained through personal communication with the primary author
Risk of bias
Item
Authors’ judgement
Allocation concealment?
Yes
Description
Söderman 2000
Methods
Randomisation: No description of method, participants randomised by clusters (teams)
Loss to follow up: 81 (59 in intervention group, 22 in control group)
Intention to treat analysis: No
Blinding of outcome assessors: No
Blinding of participants: No
Participants
Location: Sweden. Female soccer players from 13 different teams playing in the second and third Swedish divisions
Population: 221 female soccer players of 13 different teams were recruited (mean age 20) undergoing 28 weeks of
training (102 sessions)
Period of study: April - October 1998
Inclusion criteria: Not stated
Exclusion criteria: Not stated
Interventions
Intervention group (N = 121): Standard soccer practice, games and physical training. In addition the training
group performed a special training programme consisting of 10-15 min of balance board training per day for first
30 days then 3 times per week for a further 6 months. All the players were given their own balance board and were
provided with a printed handout presenting the training programme. The programme contained five exercises with
progressively increasing degree of difficulty. The height of the balance board could be elevated to increase the degree
of difficulty. The players were standing on one leg at a time with their knee in a slightly flexed position. The exercises
were carried out for 15 seconds, 3 times on each leg per session (48 sessions)
Control Group (N = 100): Standard soccer practice, games and physical training.
Outcomes
1. Incidence of lower limb injury defined by orthopaedic surgeons (absence from scheduled practice session or game
until they were able to return to full activity in games and/or practice sessions)
2. Severity: minor injuries (< 7 days lost from training or games); moderate injuries (7 to 30 days lost); and major
injuries ( > 30 days lost)
3. Postural sway-balance index (balance index)
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
22
Söderman 2000
(Continued)
4. Flexibility (hamstring/dorsiflexors)
Notes
It was not possible through personal communication to obtain the number of participants sustaining hamstring
injury and the results extracted only represent the total number of hamstring injuries occurring in the intervention
and control groups
Van Mechelen 1993
Methods
Randomisation: No description of method, although mention of “black box design”
Loss to follow up: 95 (51 in intervention group, 44 in control group)
Intention to treat analysis: Not possible
Blinding of outcome assessors: No
Blinding of participants: No
Participants
Location: Amsterdam, Netherlands. Male civil servants (recreational runners)
Population: 421 male civil servants, who were recreational runners, were recruited undergoing 16 weeks of training
Age range: Not stated
Period of study: September 1988 - January 1989
Inclusion criteria: Healthy, no injuries at the time of recruitment, not on sick leave, running at least 10km/week all
year round, and non-professional sportsmen
Exclusion Criteria: For reasons of homogeneity and because of relatively small number of responding women, all
female volunteers were excluded. No mention of previous history of injury
Interventions
Intervention group (N = 210): Information on warm up/cool down and stretching exercises explained by the coach
and performed by participants before and after each running session. Protocol: 6 minutes of running as a warm-up,
3 minutes of loosening exercises, and 10 minutes of stretching exercises to major lower limb muscles (3 repetitions
of static stretches held for 10 seconds to each muscle group)
Control group (N = 211): No intervention, instructed to carry on running as per usual and record running distance,
running time and occurrence of injury
Outcomes
1. Incidence of lower limb soft tissue injury per 1000 hours of running defined by a physician (injury as a result of
running and caused: i) the subject to stop running, ii) the subject could not run on the next occasion, iii) the subject
could not go to work the next day, iv) the subject needed medical attention or iv) the subject suffered from pain or
stiffness during 10 subsequent days while running)
2. Knowledge and attitude scores towards the intervention programme
3. Compliance
4. Exposure to running distance and running time
Notes
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
23
Characteristics of excluded studies [ordered by study ID]
Study
Reason for exclusion
Arnason 2005
No data on hamstring injuries. Investigated the use of a video based awareness programme to prevent soccer
injuries. Data request sent 28/03/07
Arnason 2006
Not an RCT. Intervention programs consisting of warm-up stretching, flexibility and/or eccentric strength
training to prevent hamstring strains in elite soccer
Bixler 1992
No data on hamstring injuries. Investigates stretching routine during half-time in prevention of injuries in the
during the third quarter of a game. However does not define injury by anatomical location
Cabry 2000
Never published and no useable data. Investigated implementing hamstring stretches within an already established training program and measured the incidence of hamstring injury. Data request sent 28/03/07
Cross 1999
Not an RCT and no usable data on hamstring injuries. Analysis of the incidence of musculotendinous strains
among the players, incorporation of a lower extremity stretching program. Does not define injury by anatomical
location. Data request sent 29/03/07
Ekstrand 1983
No usable data on hamstring injuries. The intervention programme was based on previous studies of injury
mechanisms. It comprised: correction of training, provision of optimum equipment, prophylactic ankle taping,
controlled rehabilitation, information about the importance of disciplined play and the increased risk of injury
at training camps, and correction and supervision by doctor(s) and physiotherapist(s). Injury was not defined
by anatomical location. Data request sent 27/03/07
Hartig 1999
No usable data on hamstring injuries. Efficacy of hamstring flexibility by adding three hamstring stretching
sessions to their already scheduled fitness programme. Injury not defined by anatomical location sufficiently
Heidt 2000
Not an RCT. Intervention programme consisting of plyometric training to prevent injury incorporating sportspecific cardiovascular conditioning, sport cord drills, strength training, and flexibility. The 300 players were
evaluated over one year, which included two seasons, the school season and then the select season. Random
selection occurred after the school season but injury surveillance was throughout the year
Hägglund 2007
The intervention was aimed at preventing reinjury and only implemented after initial injury occurrence. It was
excluded because the study was focusing on interventions for people with existing lower-limb musculoskeletal
injuries. Injured participants were provided with information about risk factors for reinjury, rehabilitation
principles, and a 10-step progressive rehabilitation programme including return to play criteria
Larsen 2002
No data on hamstring injury prevention. Custom-made biomechanic shoe orthoses worn in military boots were
provided to all in the study group during the three-month intervention period to see if their use prevented
problems in the back and lower extremities. Data request sent 23/06/07
Olsen 2005
No usable data on hamstring injuries. Cluster RCT of exercise including Nordic hamstring stretches to prevent
lower limb injuries in youth sports. Injury not defined by anatomical location sufficiently. Data request sent
23/06/07
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
24
(Continued)
Pope 2000
No usable data on hamstring injury prevention. Investigated the effect of muscle stretching during warm-up
on the risk of exercise-related injury. Injury not defined by anatomical location sufficiently. Data request sent
20/06/06
Rudzki 1997
No usable data on hamstring injury prevention. Investigated the effect of a substituted weighted-march activity
for all formal run periods in the physical training program. Data request sent 23/06/07
Verrall 2003
Not an RCT, never published and no useable data. Preventing hamstring muscle strain injury: sport specific
exercise in trunk flexion and eccentric hamstring stretching in reducing injury incidence
Wedderkopp 1999
No usable data on hamstring injury prevention. Prevention of injuries investigated by getting all players to a)
use individual ankle disks for 10 to15 minutes at all practice sessions, b) perform at least one functional activity
each muscle group (e.g. one and two leg jumps on stairs for lower extremities) to ensure a thorough warm-up.
Data request sent 23/06/07
Withnall 2006
No usable data on hamstring injury prevention. Participants were randomised to receive either standard issue
Saran non-shock absorbing insoles, or shock absorbing Sorbothane or Poron insoles, on a 1:1:1 basis to investigate
any difference in lower limb injury. Data request sent 24/06/07
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
25
DATA AND ANALYSES
Comparison 1. Strengthening protocols versus control
Outcome or subgroup title
1 Participants sustaining hamstring
injury
1.1 Mixed population: no or
previous history of hamstring
injury
1.2 ’Hisk risk’: previous
hamstring injury or reduced
hamstring function
2 Participants sustaining hamstring
injury: alternative analyses
2.1 Moderate or major injury
(1 week or more off )
2.2 Best compliers (at least 2
sessions attended)
3 Participants sustaining lower
limb injuries
No. of
studies
No. of
participants
3
287
Risk Ratio (M-H, Random, 95% CI)
0.83 [0.26, 2.65]
2
250
Risk Ratio (M-H, Random, 95% CI)
0.61 [0.16, 2.30]
1
37
Risk Ratio (M-H, Random, 95% CI)
2.71 [0.35, 20.79]
2
Risk Ratio (M-H, Fixed, 95% CI)
Totals not selected
1
Risk Ratio (M-H, Fixed, 95% CI)
Not estimable
1
Risk Ratio (M-H, Fixed, 95% CI)
Not estimable
1
Risk Ratio (M-H, Fixed, 95% CI)
Totals not selected
Statistical method
Effect size
Comparison 2. Manual therapy protocol versus control
Outcome or subgroup title
1 Participants sustaining a
hamstring injury
2 Participants sustaining lower
limb injuries
2.1 Lower limb muscle strain
2.2 Non-contact knee injury
No. of
studies
No. of
participants
Statistical method
Effect size
1
Risk Ratio (M-H, Fixed, 95% CI)
Totals not selected
1
Risk Ratio (M-H, Fixed, 95% CI)
Totals not selected
1
1
Risk Ratio (M-H, Fixed, 95% CI)
Risk Ratio (M-H, Fixed, 95% CI)
Not estimable
Not estimable
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
26
Comparison 3. Proprioceptive training protocol versus control
Outcome or subgroup title
1 Incidence of hamstring injury
1.1 Follow-up data
1.2 Intention-to-treat analysis
based on hamstring injury
control rate
2 Incidence of hamstring injuries adjustment for clustering
3 Incidence of all lower limb
injuries
3.1 Follow-up data
3.2 Intention-to-treat analysis
based on lower limb injury
control rate
4 Incidence of all lower limb
injuries - adjustment for
clustering
No. of
studies
No. of
participants
Statistical method
Effect size
2
2
2
Odds Ratio (M-H, Fixed, 95% CI)
Odds Ratio (M-H, Fixed, 95% CI)
Odds Ratio (M-H, Fixed, 95% CI)
Totals not selected
Not estimable
Not estimable
2
Risk Ratio (Fixed, 95% CI)
Totals not selected
2
Risk Ratio (M-H, Fixed, 95% CI)
Totals not selected
2
2
Risk Ratio (M-H, Fixed, 95% CI)
Risk Ratio (M-H, Fixed, 95% CI)
Not estimable
Not estimable
2
Risk Ratio (Fixed, 95% CI)
Totals not selected
Comparison 4. Warm-up, cool-down and stretching protocol versus control
Outcome or subgroup title
1 Incidence of hamstring injury
2 Incidence of all lower limb
injuries
No. of
studies
1
1
No. of
participants
Statistical method
Risk Ratio (M-H, Fixed, 95% CI)
Risk Ratio (M-H, Fixed, 95% CI)
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
Effect size
Totals not selected
Totals not selected
27
Analysis 1.1. Comparison 1 Strengthening protocols versus control, Outcome 1 Participants sustaining
hamstring injury.
Review:
Interventions for preventing hamstring injuries
Comparison: 1 Strengthening protocols versus control
Outcome: 1 Participants sustaining hamstring injury
Study or subgroup
Intervention
Control
n/N
n/N
Risk Ratio
MH,Random,95%
CI
Weight
Risk Ratio
MH,Random,95%
CI
1 Mixed population: no or previous history of hamstring injury
Askling 2003
3/15
10/15
37.7 %
0.30 [ 0.10, 0.88 ]
Gabbe 2006
10/114
8/106
41.9 %
1.16 [ 0.48, 2.83 ]
129
121
79.5 %
0.61 [ 0.16, 2.30 ]
Subtotal (95% CI)
Total events: 13 (Intervention), 18 (Control)
Heterogeneity: Tau2 = 0.67; Chi2 = 3.63, df = 1 (P = 0.06); I2 =72%
Test for overall effect: Z = 0.73 (P = 0.47)
2 ’Hisk risk’: previous hamstring injury or reduced hamstring function
Engebretsen 2008
5/24
1/13
20.5 %
2.71 [ 0.35, 20.79 ]
Subtotal (95% CI)
24
13
20.5 %
2.71 [ 0.35, 20.79 ]
153
134
100.0 %
0.83 [ 0.26, 2.65 ]
Total events: 5 (Intervention), 1 (Control)
Heterogeneity: not applicable
Test for overall effect: Z = 0.96 (P = 0.34)
Total (95% CI)
Total events: 18 (Intervention), 19 (Control)
Heterogeneity: Tau2 = 0.63; Chi2 = 5.29, df = 2 (P = 0.07); I2 =62%
Test for overall effect: Z = 0.31 (P = 0.75)
0.01
0.1
Favours intervention
1
10
100
Favours control
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
28
Analysis 1.2. Comparison 1 Strengthening protocols versus control, Outcome 2 Participants sustaining
hamstring injury: alternative analyses.
Review:
Interventions for preventing hamstring injuries
Comparison: 1 Strengthening protocols versus control
Outcome: 2 Participants sustaining hamstring injury: alternative analyses
Study or subgroup
Intervention
Control
n/N
n/N
Risk Ratio
Risk Ratio
M-H,Fixed,95% CI
M-H,Fixed,95% CI
1 Moderate or major injury (1 week or more off)
Askling 2003
2/15
3/15
0.67 [ 0.13, 3.44 ]
7/53
0.30 [ 0.07, 1.39 ]
2 Best compliers (at least 2 sessions attended)
Gabbe 2006
2/50
0.01
0.1
1
Favours intervention
10
100
Favours control
Analysis 1.3. Comparison 1 Strengthening protocols versus control, Outcome 3 Participants sustaining
lower limb injuries.
Review:
Interventions for preventing hamstring injuries
Comparison: 1 Strengthening protocols versus control
Outcome: 3 Participants sustaining lower limb injuries
Study or subgroup
Engebretsen 2008
Intervention
Control
n/N
n/N
14/24
9/13
Risk Ratio
Risk Ratio
M-H,Fixed,95% CI
M-H,Fixed,95% CI
0.84 [ 0.51, 1.38 ]
0.01
0.1
Favours intervention
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
1
10
100
Favours control
29
Analysis 2.1. Comparison 2 Manual therapy protocol versus control, Outcome 1 Participants sustaining a
hamstring injury.
Review:
Interventions for preventing hamstring injuries
Comparison: 2 Manual therapy protocol versus control
Outcome: 1 Participants sustaining a hamstring injury
Study or subgroup
Hoskins 2008
Intervention
Control
n/N
n/N
1/28
5/29
Risk Ratio
Risk Ratio
M-H,Fixed,95% CI
M-H,Fixed,95% CI
0.21 [ 0.03, 1.66 ]
0.01
0.1
1
Favours intervention
10
100
Favours control
Analysis 2.2. Comparison 2 Manual therapy protocol versus control, Outcome 2 Participants sustaining
lower limb injuries.
Review:
Interventions for preventing hamstring injuries
Comparison: 2 Manual therapy protocol versus control
Outcome: 2 Participants sustaining lower limb injuries
Study or subgroup
Intervention
Control
n/N
n/N
Risk Ratio
Risk Ratio
1/28
8/29
0.13 [ 0.02, 0.97 ]
1/28
7/29
0.15 [ 0.02, 1.13 ]
M-H,Fixed,95% CI
M-H,Fixed,95% CI
1 Lower limb muscle strain
Hoskins 2008
2 Non-contact knee injury
Hoskins 2008
0.01
0.1
Favours intervention
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
1
10
100
Favours control
30
Analysis 3.1. Comparison 3 Proprioceptive training protocol versus control, Outcome 1 Incidence of
hamstring injury.
Review:
Interventions for preventing hamstring injuries
Comparison: 3 Proprioceptive training protocol versus control
Outcome: 1 Incidence of hamstring injury
Study or subgroup
Intervention
Control
Odds Ratio
Odds Ratio
n/N
n/N
M-H,Fixed,95% CI
M-H,Fixed,95% CI
1/494
3/426
0.29 [ 0.03, 2.76 ]
1/62
7/78
0.17 [ 0.02, 1.39 ]
1 Follow-up data
Emery 2007
Söderman 2000
2 Intention-to-treat analysis based on hamstring injury control rate
Emery 2007
1/505
3/426
0.28 [ 0.03, 2.70 ]
Söderman 2000
6/121
9/100
0.53 [ 0.18, 1.54 ]
0.01
0.1
1
Favours intervention
10
100
Favours control
Analysis 3.2. Comparison 3 Proprioceptive training protocol versus control, Outcome 2 Incidence of
hamstring injuries - adjustment for clustering.
Review:
Interventions for preventing hamstring injuries
Comparison: 3 Proprioceptive training protocol versus control
Outcome: 2 Incidence of hamstring injuries - adjustment for clustering
Study or subgroup
log [Risk Ratio]
Risk Ratio
Risk Ratio
(SE)
IV,Fixed,95% CI
IV,Fixed,95% CI
Emery 2007
-1.273 (1.267)
0.28 [ 0.02, 3.35 ]
Söderman 2000
-0.635 (0.573)
0.53 [ 0.17, 1.63 ]
0.01
0.1
Favours intervention
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
1
10
100
Favours control
31
Analysis 3.3. Comparison 3 Proprioceptive training protocol versus control, Outcome 3 Incidence of all
lower limb injuries.
Review:
Interventions for preventing hamstring injuries
Comparison: 3 Proprioceptive training protocol versus control
Outcome: 3 Incidence of all lower limb injuries
Study or subgroup
Intervention
Control
n/N
n/N
Risk Ratio
Risk Ratio
89/494
96/426
0.80 [ 0.62, 1.03 ]
28/62
31/78
1.14 [ 0.77, 1.67 ]
M-H,Fixed,95% CI
M-H,Fixed,95% CI
1 Follow-up data
Emery 2007
Söderman 2000
2 Intention-to-treat analysis based on lower limb injury control rate
Emery 2007
91/505
96/426
0.80 [ 0.62, 1.03 ]
Söderman 2000
51/121
40/100
1.05 [ 0.77, 1.45 ]
0.01
0.1
1
Favours intervention
10
100
Favours control
Analysis 3.4. Comparison 3 Proprioceptive training protocol versus control, Outcome 4 Incidence of all
lower limb injuries - adjustment for clustering.
Review:
Interventions for preventing hamstring injuries
Comparison: 3 Proprioceptive training protocol versus control
Outcome: 4 Incidence of all lower limb injuries - adjustment for clustering
Study or subgroup
Emery 2007
Söderman 2000
log [Risk Ratio]
Risk Ratio
Risk Ratio
(SE)
IV,Fixed,95% CI
IV,Fixed,95% CI
-0.223 (0.143)
0.80 [ 0.60, 1.06 ]
0.048 (0.169)
1.05 [ 0.75, 1.46 ]
0.01
0.1
Favours intervention
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
1
10
100
Favours control
32
Analysis 4.1. Comparison 4 Warm-up, cool-down and stretching protocol versus control, Outcome 1
Incidence of hamstring injury.
Review:
Interventions for preventing hamstring injuries
Comparison: 4 Warm-up, cool-down and stretching protocol versus control
Outcome: 1 Incidence of hamstring injury
Study or subgroup
Van Mechelen 1993
Intervention
Control
n/N
n/N
3/159
3/167
Risk Ratio
Risk Ratio
M-H,Fixed,95% CI
M-H,Fixed,95% CI
1.05 [ 0.22, 5.13 ]
0.01
0.1
1
Favours intervention
10
100
Favours control
Analysis 4.2. Comparison 4 Warm-up, cool-down and stretching protocol versus control, Outcome 2
Incidence of all lower limb injuries.
Review:
Interventions for preventing hamstring injuries
Comparison: 4 Warm-up, cool-down and stretching protocol versus control
Outcome: 2 Incidence of all lower limb injuries
Study or subgroup
Van Mechelen 1993
Intervention
Control
n/N
n/N
23/159
20/167
Risk Ratio
Risk Ratio
M-H,Fixed,95% CI
M-H,Fixed,95% CI
1.21 [ 0.69, 2.11 ]
0.01
0.1
Favours intervention
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
1
10
100
Favours control
33
ADDITIONAL TABLES
Table 1. Methodological quality assessment scheme
Items
Scores
Notes
A. Was an effective method of randomisa- Y = yes, e.g. use of random tables
tion used?
? = no description of method
N = quasi-randomised method only
To achieve ’Y’, a random (unpredictable)
assignment sequence is required
B. Was the assigned treatment adequately Y = method did not allow disclosure of asconcealed prior to allocation?
signment
? = small but possible chance of disclosure
of assignment or unclear
N = quasi-randomised or open list/tables
For example, a method using centralised (e.
g. allocation by a central office unaware of
subject characteristics) or independentlycontrolled randomisation
C. Were the outcomes of participants who Y = no dropouts or withdrawals well dewithdrew described and included in the scribed and accounted for in analysis.
analysis (intention to treat)?
? = withdrawals described and analysis not
possible
N = no mention, inadequate mention, or
obvious differences and no adjustment
D. Were the outcome assessors blind to as- Y = effective action taken to blind outcome
signment status?
assessors
? = small or moderate chance of unblinding
of outcome assessors
N = not possible, or not mentioned (unless
double-blind), or possible but not done
E. Were the treatment and control groups Y = good comparability of groups, or con- The principal confounders considered were
comparable at entry?
founding adjusted for in analysis
sex, age, previous overuse lower-limb injury
? = confounding small; mentioned but not and prior physical activity profile
adjusted for
N = large potential for confounding, or not
discussed
F. Were the participants blind to assign- Y = effective action taken to blind particiment status after allocation?
pants
? = small or moderate chance of unblinding
of participants
N = not possible, or not mentioned (unless
double-blind), or possible but not done
G. Were the treatment providers blind to Y = effective action taken to blind treatment
assignment status?
providers
? = small or moderate chance of unblinding
of treatment providers
N = not possible, or not mentioned (unless
double-blind), or possible but not done
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
34
Table 1. Methodological quality assessment scheme
(Continued)
H. Were care programmes, other than the Y = care programmes clearly identical
trial options, identical?
? = clear but trivial differences
N = not mentioned or clear and important
differences in care
Examples of clinically important differences in other interventions (co-interventions) are those which could act as active
measures for prevention of hamstring injuries: training programmes, advice on activity and etc
I. Were the inclusion and exclusion criteria Y = clearly defined
clearly defined?
? = inadequately defined
N = not defined
To achieve ’Y’, the inclusion or exclusion
of individuals with a) previous hamstring
injuries and b) previous exposure to trial
intervention needs to be confirmed
J. Were the interventions clearly defined?
Y = clearly defined interventions are applied
with a standardised protocol
? = clearly defined interventions are applied
but the application protocol is not standardised
N = intervention and/or application protocol are poorly or not defined
K. Were the outcome measures used clearly Y = optimal
defined? (by outcome)
? = adequate
N = not defined, not adequate
To achieve ’Y’, the method and strategy of
data collection need to be clearly defined
L. Were diagnostic tests used in outcome Y = clearly defined and best available tests
assessment clinically useful? (by outcome) are applied with a standardised protocol
? = clearly defined tests are applied but the
application protocol is not standardised
N = tests and/or application protocol are
poorly or not defined
M. Is the surveillance active, and of clini- Y = active surveillance and appropriate ducally appropriate duration?(by outcome)
ration
? = active surveillance, but inadequate duration
N = surveillance not active or not defined
N. Was compliance of participants dis- Y = compliance greater than 90% in each
closed?
group after randomisation
? = compliance with allocated procedure reported
N = compliance not mentioned
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
Measures of compliance are likely to vary
and thus the way of estimating the 90%
compliance will depend on the measures
used in individual trials
35
Table 2. Intervention period
Study ID
Period of intervention Total no. of intervention Hours
(weeks)
sessions
week
of
exposure/ Total hours of exposure
Askling 2003
10
16
Not stated
Not stated
Emery 2007
18
Not stated
Not stated
Not stated
Engebretsen 2008
10
24
Not stated
Not stated
Gabbe 2006
12
5
Not stated
Not stated
Hoskins 2008
30
15
Not stated
Not stated
Söderman 2000
28
102
Not stated
Not stated
Van Mechelen 1993
16
Not stated
Not stated
Not stated
Table 3. Results of methodological quality assessment for individual trials
Category/
Study
Askling 2003
Emery 2007
Engebretsen
2008
Gabbe 2006
Hoskins 2008 Söderman
2000
Van Mechelen
1993
A. Sequence ?
generation
Y
Y
Y
Y
?
?
B. Allocation ?
concealment
Y
?
?
Y
?
?
C. Intention- N
to-treat analysis
N
Y
Y
N
N
N
D. Assessor ?
blinding
Y
N
?
Y
N
N
E.
Baseline Y
comparability
Y
N
Y
Y
Y
Y
F. Participant N
blinding
?
N
N
N
N
N
G. Interven- N
tion provider
blinding
Y
N
N
N
N
N
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
36
Table 3. Results of methodological quality assessment for individual trials
(Continued)
H. Care pro- Y
gramme comparability
Y
Y
Y
N
N
N
I. Inclusion Y
and exclusion
criteria
Y
Y
Y
Y
N
Y
J. Well defined Y
interventions
N
Y
Y
N
N
?
K. Well de- Y
fined outcome
measures
Y
Y
Y
Y
Y
?
L.
Clini- Y
cally useful diagnostic tests
?
Y
?
Y
Y
?
M. Active and ?
sufficiently long
follow-up
Y
N
Y
Y
Y
N
N.Compliance reported
?
?
?
N
?
?
N
APPENDICES
Appendix 1. Search strategies
The Cochrane Library (Wiley InterScience interface)
#1 (hamstring* or semimembran* or semitend* or biceps femoris) :ti,ab,kw in Clinical Trials
#2 MeSH descriptor Tendon Injuries explode all trees
#3 MeSH descriptor Athletic Injuries, this term only
#4 MeSH descriptor Sprains and Strains, this term only
#5 MeSH descriptor Leg Injuries, this term only
#6 MeSH descriptor Knee Injuries, this term only
#7 (#2 OR #3 OR #4 OR #5 OR #6)
#8 (#1 AND #7)
#9 ((injur* or rupture* or avuls* or tendinitis or tendonitis or tendinosis or tendonosis or strain* or sprain* or tear*) NEAR (hamstring*
or semimembran* or semitend* or biceps femoris)):ti,ab,kw in Clinical Trials
#10 (#8 OR #9)
Interventions for preventing hamstring injuries (Review)
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37
MEDLINE (Ovid interface)
1. (hamstring$ or semimembran$ or semitend$ or biceps femoris).tw.
2. exp Tendon Injuries/pc [Prevention & Control]
3. Athletic Injuries/pc [Prevention & Control]
4. “Sprains and Strains”/pc [Prevention & Control]
5. Leg Injuries/pc [Prevention & Control]
6. Knee Injuries/pc [Prevention & Control]
7. or/2-6
8. and/1,7
9. ((injur$ or rupture$ or avuls$ or tend#nitis or tend#nosis or strain$ or sprain$ or tear$) adj3 (hamstring$ or semimembran$ or
semitend$ or biceps femoris)).tw.
10. or/8-9
11. randomized controlled trial.pt.
12. controlled clinical trial.pt.
13. Randomized Controlled Trials/
14. Random Allocation/
15. Double Blind Method/
16. Single Blind Method/
17. or/11-16
18. Animals/ not Humans/
19. 17 not 18
20. clinical trial.pt.
21. exp Clinical Trials as topic/
22. (clinic$ adj25 trial$).tw.
23. ((singl$ or doubl$ or trebl$ or tripl$) adj25 (blind$ or mask$)).tw.
24. Placebos/
25. placebo$.tw.
26. random$.tw.
27. Research Design/
28. or/20-27
29. 28 not 18
30. 29 not 19
31. Comparative Study/
32. and/10,31
EMBASE (Ovid interface)
1 Hamstring/ or (hamstring$ or semimembran$ or semitend$ or biceps femoris).tw.
2 exp Tendon Injury/pc [Prevention]
3 Sport Injury/pc [Prevention]
4 Sprain/pc [Prevention]
5 Leg Injury/pc [Prevention]
6 Knee Injury/pc [Prevention]
7 or/2-6
8 and/1,7
9 ((injur$ or rupture$ or avuls$ or tend#nitis or tend#nosis or strain$ or sprain$ or tear$) adj3 (hamstring$ or semimembran$ or
semitend$ or biceps femoris)).tw.
10 or/8-9
11 exp Randomized Controlled trial/
12 exp Double Blind Procedure/
13 exp Single Blind Procedure/
14 exp Crossover Procedure/
15 Controlled Study/
Interventions for preventing hamstring injuries (Review)
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38
16 or/11-15
17 ((clinical or controlled or comparative or placebo or prospective$ or randomi#ed) adj3 (trial or study)).tw.
18 (random$ adj7 (allocat$ or allot$ or assign$ or basis$ or divid$ or order$)).tw.
19 ((singl$ or doubl$ or trebl$ or tripl$) adj7 (blind$ or mask$)).tw.
20 (cross?over$ or (cross adj1 over$)).tw.
21 ((allocat$ or allot$ or assign$ or divid$) adj3 (condition$ or experiment$ or intervention$ or treatment$ or therap$ or control$ or
group$)).tw.
22 or/17-21
23 or/16,22
24 limit 23 to human
25 and/10,24
CINAHL (Ovid interface)
1 Hamstring muscles/ or (hamstring$ or semimembran$ or semitend$ or biceps femoris).tw.
2 exp Tendon Injuries/pc [Prevention and Control]
3 Athletic Injuries/pc [Prevention and Control]
4 “Sprains and Strains”/pc [Prevention and Control]
5 Leg Injuries/pc [Prevention and Control]
6 Knee Injuries/pc [Prevention and Control]
7 or/2-6
8 and/1,7
9 ((injur$ or rupture$ or avuls$ or tend#nitis or tend#nosis or strain$ or sprain$ or tear$) adj3 (hamstring$ or semimembran$ or
semitend$ or biceps femoris)).tw.
10 or/8-9
11 exp Clinical Trials/
12 exp Evaluation Research/
13 exp Comparative Studies/
14 exp Crossover Design/
15 clinical trial.pt.
16 or/11-15
17 ((clinical or controlled or comparative or placebo or prospective or randomi#ed) adj3 (trial or study)).tw.
18 (random$ adj7 (allocat$ or allot$ or assign$ or basis$ or divid$ or order$)).tw.
19 ((singl$ or doubl$ or trebl$ or tripl$) adj7 (blind$ or mask$)).tw.
20 (cross?over$ or (cross adj1 over$)).tw.
21 ((allocat$ or allot$ or assign$ or divid$) adj3 (condition$ or experiment$ or intervention$ or treatment$ or therap$ or control$ or
group$)).tw.
22 or/17-21
23 or/16,22
24 and/10,23
SPORTDiscus (Ovid interface)
1 ((injur$ or rupture$ or avuls$ or tend#nitis or tend#nosis or strain$ or sprain$ or tear$) adj3 (hamstring$ or semimembran$ or
semitend$ or biceps femoris)).tw.
2 ((clinic$ or controlled or comparative or placebo or prospective or randomi#ed) adj3 (trial or study)).tw.
3 (random$ adj7 (allocat$ or allot$ or assign$ or basis$ or divid$ or order$)).tw.
4 (cross?over$ or (cross adj1 over$)).tw.
5 randomi?ed control$ trial$.tw.
6 ((allocat$ or allot$ or assign$ or divid$) adj3 (condition$ or experiment$ or intervention$ or treatment$ or therap$ or control$ or
group$)).tw.
7 placebo$.tw.
8 ((singl$ or doubl$ or trebl$ or tripl$) adj7 (blind$ or mask$)).tw.
Interventions for preventing hamstring injuries (Review)
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39
9 or/2-8
10 and/1,9
AMED (Ovid interface)
1 (hamstring$ or semimembran$ or semitend$ or biceps femoris).tw.
2 Tendon injuries/
3 Athletic injuries/
4 “Sprains and strains”/
5 Leg injuries/
6 Knee injuries/
7 or/2-6
8 and/1,7
9 ((injur$ or rupture$ or avuls$ or tend#nitis or tend#nosis or strain$ or sprain$ or tear$) adj3 (hamstring$ or semimembran$ or
semitend$ or biceps femoris)).tw.
10 or/8-9
11 randomized controlled trial.pt.
12 controlled clinical trial.pt.
13 Randomized Controlled Trials/
14 Random Allocation/
15 Double-Blind Method/
16 or/11-15
17 Animal/ not Human/
18 16 not 17
19 clinical trial.pt.
20 exp Clinical trials/
21 (clinic$ adj25 trial$).tw.
22 ((singl$ or doubl$ or trebl$ or tripl$) adj (mask$ or blind$)).tw.
23 Placebos/
24 placebo$.tw.
25 random$.tw.
26 exp Research design/
27 (latin adj square).tw.
28 or/19-27
29 28 not 17
30 29 not 18
31 and/10,30
PEDro (accessed via www.pedro.org.au)
’Abstract & Title’: hamstring
’Method’: clinical trial
Match all search terms (AND)
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
40
WHAT’S NEW
Last assessed as up-to-date: 28 February 2009.
Date
Event
Description
26 November 2009
Amended
Contact author’s email address updated
HISTORY
Protocol first published: Issue 4, 2007
Review first published: Issue 1, 2010
Date
Event
Description
23 May 2008
Amended
Converted to new review format.
CONTRIBUTIONS OF AUTHORS
Elliott Goldman (EF) conceived the original idea for the review, wrote the first drafts of the protocol and review, and performed the
data collection and analysis.
Diana Jones (DJ) participated in the writing of the protocol and review, and participated in the data collection and analysis.
DECLARATIONS OF INTEREST
None known.
SOURCES OF SUPPORT
Internal sources
• Northumbria University, UK.
Interventions for preventing hamstring injuries (Review)
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41
External sources
• No sources of support supplied
INDEX TERMS
Medical Subject Headings (MeSH)
Athletic Injuries [∗ prevention & control]; Muscle, Skeletal [∗ injuries]; Randomized Controlled Trials as Topic; Thigh [injuries]
MeSH check words
Adolescent; Adult; Child; Female; Humans; Male; Young Adult
Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
42