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.

T A B L E O F C O N T E N T S
1HEADER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2PLAIN LANGUAGE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12AUTHORS’ CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17CHARACTERISTICS OF STUDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26DATA AND ANALYSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 1.1. Comparison 1 Strengthening protocols versus control, Outcome 1 Participants sustaining hamstring injury. 28
Analysis 1.2. Comparison 1 Strengthening protocols versus control, Outcome 2 Participants sustaining hamstring injury:
alternative analyses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Analysis 1.3. Comparison 1 Strengthening protocols versus control, Outcome 3 Participants sustaining lower limb
injuries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Analysis 2.1. Comparison 2 Manual therapy protocol versus control, Outcome 1 Participants sustaining a hamstring
injury. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Analysis 2.2. Comparison 2 Manual therapy protocol versus control, Outcome 2 Participants sustaining lower limb
injuries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Analysis 3.1. Comparison 3 Proprioceptive training protocol versus control, Outcome 1 Incidence of hamstring injury. 31
Analysis 3.2. Comparison 3 Proprioceptive training protocol versus control, Outcome 2 Incidence of hamstring injuries -
adjustment for clustering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Analysis 3.3. Comparison 3 Proprioceptive training protocol versus control, Outcome 3 Incidence of all lower limb
injuries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Analysis 3.4. Comparison 3 Proprioceptive training protocol versus control, Outcome 4 Incidence of all lower limb injuries
- adjustment for clustering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Analysis 4.1. Comparison 4 Warm-up, cool-down and stretching protocol versus control, Outcome 1 Incidence of
hamstring injury. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Analysis 4.2. Comparison 4 Warm-up, cool-down and stretching protocol versus control, Outcome 2 Incidence of all lower
limb injuries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
33ADDITIONAL TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
37APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
40WHAT’S NEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
41HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
41CONTRIBUTIONS OF AUTHORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
41DECLARATIONS OF INTEREST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
41SOURCES OF SUPPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
42INDEX TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
iInterventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

[Intervention Review]
Interventions for preventing hamstring injuries
Elliott F Goldman1, Diana E Jones2
1Synergy Healthcare, Bedlington, UK. 2School 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.
A B S T R A C T
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 in-
terventions 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
1Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

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.
P L A I N L A N G U A G E S U M M A R Y
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.
B A C K G R O U N D
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 ex-
tension 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 sever-
ity 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 palpa-
tion, range of motion and muscle testing (Kujala 1997). Magnetic
2Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

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 re-
quiring bursts of speed or rapid acceleration and deceleration. Re-
cent 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 ac-
tion. 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 ini-
tial 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 profes-
sional footballer to miss approximately three matches or weeks of
play (Woods 2004). Hamstring injuries are often serious requir-
ing rehabilitation and they tend to recur (Croisier 2004;Orchard
2002a). For instance, Orchard 2002b reported a high rate of re-
currence in 34% of primary cases over the course of a Australian
football season.
The causes of hamstring injuries are complicated and multifac-
torial (Gleim 1997). In general, a distinction in risk factors has
been made between so-called intrinsic (person-related) and extrin-
sic (environment-related) risk factors (Inklar 1994;Taimela 1990;
Van Mechelen 1992). Intrinsic factors include hamstring mus-
cle 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 activ-
ity, poor playing surfaces and unsuitable training and sports spe-
cific activities (Hawkins 1999;Safran 1988). Orchard 2001 sug-
gested 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 mea-
sures.
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); neuromus-
cular injury prevention strategies including proprioceptive balance
training (Emery 2007;Turl 1998); chiropractic, spinal manipula-
tive 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); educa-
tion, 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.
O B J E C T I V E S
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;
3Interventions for preventing hamstring injuries (Review)
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.