1. Hamstring
Strain Injuries
3003PES – Injury Prevention and Management
By DION OBST

2. Table of Contents
• Introduction • Mechanism of Injury
• Definitions • Clinical Diagnosis
• Aetiology • Differential Diagnosis
• Anatomy of the Hamstring • Phases of Injury and Treatment
• Physiology of the Hamstring • Rehabilitation
• Muscle Physiology • Rehabilitation and Injury Prevention
•Young athletes and Hamstring Strains • Literature Review
• Biomechanics of the Hamstring • References

3. Introduction
• A variety of studies have found that hamstring injuries are the
most common injury in AFL, athletics (sprinting), soccer, cricket and
touch football (Hoskins, 2005).
•Hamstring strain injuries typically occur in sports that involve rapid
high speed activity, rapid acceleration and/or strenuous stretching
manoeuvres.
• Brockett et.al (2004) investigated AFL injuries and estimated
approximately 16% of all injuries cases are hamstring strains.
• The evidence suggests that the chance of re-injury to the
hamstring occurs in 34% of cases (Brockett, 2004).
Source: http://www.fotosearch.com/ Source: http://mm.afl.com.au/

4. Definitions
A muscle strain can be defined as excessive stretching or
tearing (complete or partial) of the muscle fibres and is
graded according to the severity.
Common names for a hamstring strain injury include:
• Biceps Femoris strain
• Torn ‘Hammy’
• Pulled hamstring
A hamstring strain involves stretching and/or partial tearing
of one or more of the 4 hamstring muscle groups
Source: http://www.return2fitness.co.uk

5. Aetiology
Hamstring strain injuries are graded according to their severity:
Grading Severity
Grade 1 (Mild) Small % of fibres are stretched or torn, mild pain,
minimal to no loss of strength.
Grade 2 (Mod) Significant % of torn fibres, swelling, pain with
active ROM, loss of strength, palpable deformity.
Grade 3 (Severe) Complete tearing of fibres and/or MT junction,
gross impairment, severe initial pain.
Source: http://www.sportsinjuryclinic.net
Muscles that are most susceptible to strains are those in which their
origin and insertion points span over two joints (Noonan,1999).
Untrained athletes are more prone to hamstring-related injuries
during exercise that involves eccentric muscle contraction.

6. Aetiology
The most common causal factors of Normal
hamstring strain injuries are:
• Poor flexibility and strength
• Strength imbalance between
quadriceps and hamstring muscle
groups
• Strength imbalance between gluteals
and abdominal muscle groups
• Inadequate warm-up techniques
• Previous hamstring injuries
• Over exertion or excessive stretching
• Muscle fatigue
• Differences in leg length (Increased
tension on shorter leg)
Poor flexibility Great flexibility

7. Anatomy of the
Hamstring
The hamstring comprises of 3 major muscles:
1) Biceps Femoris (long and short head)
2) Semitendinosis
3) Semimembranosis
The hamstrings span over two joints - the hip and
the knee joint
Muscle Origin Insertion
1. Ischial Tuberosity Head of Fibula (lateral side)
(long)
(short) Linea Aspera Head of Fibula (lateral side)
2. Ischial Tuberosity Tibia (medial surface)
3. Ischial Tuberosity Tibial Condyle (medial)
(Hoskins & Pollard, 2005)
Source: http://www.fotosearch.com/

8. Physiology of the
Hamstring
• Eccentric contractions of the hamstring are believed to result
in microscopic muscle damage to the muscle fibres (Brockett,
2004).
• A local inflammatory response is initiated following injury.
• This mechanism is believed to have a role in sensitizing muscle
nocioreceptors and mechanoreceptors (Morgan, 1999).
• Untrained individuals are more prone to muscle strain injuries
which may result in reductions in muscle tension and the
optimal length to generate tension is increased (Morgan, 1999).

9. Muscle Physiology
• Muscle fatigue is thought to play a major role in contributing to
muscle damage.
• Muscles that commonly experience strain type injuries are composed
of Type II (Fast-twitch) fibres (i.e. Hamstring).
• An strength imbalance may also exist between the quadriceps and the
hamstring. The quadriceps are typically stronger and therefore the
hamstrings often fatigue much faster (Petersen & Holmich, 2005).
•This results in the inability of the hamstring muscles to adequately
relax during contraction of the quadriceps, therefore strains occur
(Petersen & Holmich, 2005).
• Other causal mechanisms include changes in excitation-contraction
coupling, Ca2+ sensitivity and sarcomere recruitment (Morgan, 1999).

10. Young Athletes and
Hamstring Strains
• During growing periods, muscles and
bones have the tendency to grow at
different rates.
•Young athletes may be subjective to
hamstring strain injuries if their bones Source: https://console.clubsonline.com.au/
grow at a faster rate than their muscles.
• This causes greater stretch on the
muscle fibres and therefore a sudden
motion such as jumping may lead to
exaggerated stretch or muscle tearing
from the bone (Brockett, 2004).
Source: http://images.conquestchronicles.com/

11. Biomechanics of
the Hamstring
The biomechanical role of the hamstrings include:
• Knee Flexion (heel towards gluts)
• Hip Extension (backwards movement of leg)
• Deceleration of the knee ( quadriceps antagonist)
Source: http://www.albionrundoctor.com/

12. Biomechanics of
the Hamstring
During gait, injuries most commonly occur at the end stage of
the swing phase (Hoskins & Pollard, 2005).
MUSCLE ACTION
Semitendinosis/ Predominantly involved in hip extension. Also knee flexion
Semitendinosis and internal rotation of lower leg.
Biceps Femoris (long) Hip extension at beginning of gait cycle
Biceps Femoris Knee flexion and external rotation of the lower leg.
(Long & Short Head)
Mechanoreceptors in the ACL provide proprioceptive information
to the hamstring muscles, causing them to activate at the end of
the swing phase of gait (Hoskins & Pollard, 2005).
This may explain the reason why those who previous experienced
knee injuries are prone to hamstring strain injuries.

13. Biomechanics of
the Hamstring
A study by Askling et.al (2006), examined the differences in
the recovery period of two types of acute hamstring strains.
• A group of 18 elite sprinters an 15 dancers diagnosed with
hamstring strains were examined
• The sprinters experienced the injury during high speed
running, whereas the dancers developed the strain via slow
stretching exercises
RESULTS: Initially, the sprinters experienced the greatest loss
of function, however the dancers required significantly
greater time to return to pre-injury level:-
Median (Sprinters) – 16 weeks (range 6-50)
Median (Dancers) – 50 weeks (range 30-76)

14. Mechanisms of Injury
The evidence strongly suggests that athletes who have experienced
hamstring injuries previously, are most susceptible to recurring
hamstring strains (Orchard, 1997).
Eccentric contraction of the hamstrings is known to cause microscopic
damage to the muscle fibres. Tearing of fibres begins when the force
applied exceed 80% of the force required to agitate the muscle
(Malliaropoulos et.al,2004).
Poor technique or muscle weakness may result in a hamstring strain
during the initial stance phase of gait (Hoskins & Pollard, 2005)
It is proposed that microscopic damage is caused by the lengthening
of sarcomeres in a non-uniform manner (Brockett, 2004).
• Muscle fibres that exhibit short optimal
length capabilities are more at risk of
microscopic damage (Brockett, 2004).

15. Clinical Diagnosis
Referral of any hamstring distress is vital for
establishing correct treatment options and
preventing further injury.
Diagnosis involves an evaluation of past
history, type of action/activity performed and
physical examination.
MRI scans may be conducted to establish deep-
intramuscular strains or tearing of the
hamstring .
These scans are only performed if a negative
response to treatment occurs or the
mechanisms of injury are unknown (Hoskins &
Pollard, 2005).
*Partial tear of right hamstring tendon (red arrows)
Source: http://3.bp.blogspot.com/

16. Clinical Diagnosis
The following physical examination techniques are
commonly performed when diagnosing hamstring injuries
Straight Leg Raise – Passive leg raise with straight
knee.
Normal ROM is 80 – 90 .
Pain may be reproduced.
Comparisons are made between opposite limbs.
Source: http://bjsm.bmj.com/
Resisted Knee Flexion – Passive resistance as
patient bends knee.
Causes hamstring contraction and pain
Strength of movement is compared to opposite limb
(http://www.sportsinjuryclinic.net/)
Source: http:// http://www.chiroandosteo.com/

17. Clinical Diagnosis
Slump Test – Determines if any neural
involvement is present.
Patient straightens out one leg, bends head
downwards and points toes upwards.
Stretch is enhanced by pushing patient forward.
Symptoms such as pain shooting down the leg is a
positive indication of neural involvement.
Source: http://www.ihcatl.com/
Palpitation – Physician will touch or palpitate the
muscle to detect any deformity, pain, tension or
hole within the muscle belly and associated
structures.
(http://www.sportsinjuryclinic.net/)
Source: http://thump01.pbase.com/

18. Differential
Source: http://www.fotosearch.com/ Diagnosis
• Misdiagnosis of hamstring strain injuries is common, leading to
incorrect management techniques that can exacerbate the injury or
prolong the recovery period (Hoskins, 2005).
• Preventative techniques to decrease the chance of a hamstring
strain are imperative in professional sport.
• The sciatic nerve passes through the hamstring muscle group and
therefore an injury to the lower back may refer pain to the hamstring
region (Noonan, 1999).
• Delayed-onset muscle soreness is commonly mistaken as a strain
however the symptoms develop 24-72 hours post-exercise then
disappear. A strain results in immediate pain and functional
deterioration (Noonan, 1999).
• Hamstring pain may also be a symptom of other injuries such as
adductor strains, sacroiliac joint, gluteal trigger points and bursitis. Source: http://sussexphysio.co.uk/

19. Phases of Injury and Treatment
The following table summarises the 5 phases of injury proposed by
Petersen & Holmich (2005) and the appropriate actions to aid recovery
Phases of Injury Signs/treatment
Phase 1 (acute): • RICER treatment is important
1 - 7days Goal: Minimise swelling, pain and control haemorrhaging.
• Use of NSAIDs for short period after injury.
• Light movement techniques prevent adhesions.
Phase 2 (subacute): • Inflammatory symptoms begin to resolve.
3days – 3weeks • Basic exercise techniques promote healing and prevent
muscle atrophy. Concentric exercises introduced.
• Cardiovascular fitness should be maintained.
Phase 3 (remodelling): • Loss of flexibility due to scar tissue formation and pain.
1 – 6 weeks • Stretching performed to maintain flexibility.
• Eccentric exercise introduced (light to avoid re-injury)
Phase 4 (functional): Goal: Decrease the risk of re-injury during sport.
2wks – 6months • Sport specific strength and flexibility protocols initiated.
Phase 5 (return to comp): Goal: Maintain strength and flexibility of muscle to avoid
3wks – 6mths recurring injury.

20. Rehabilitation
Once a qualified physician has established a correct diagnosis,
there are a variety of techniques used to enhance recovery and
prevent further injury. Stretching techniques are outlined below:
STATIC STRETCHING CONTRACT – RELAX
Internal rotation External rotation STRETCHING
DYNAMIC STRETCHING
Source: Swinging of leg forward and backwards with gradual
(http://www.sportsinjuryclinic.net/) increases in height

21. Rehabilitation
A study by Malliaropoulos et.al (2004), examined two different
rehabilitation protocols to determine effectiveness of each.
80 athletes with acute hamstring strain injuries were assessed, with
rehabilitation occurring 48hrs post-injury.
One group performed one session daily and the other participated in four
per day.
Each session involved a static hamstring muscle stretch that was
sustained for 30 seconds. This was performed 4 times per session.
The results indicated that the group which participated in the greater
number of sessions (4 per day) were able to regain ROM in a shorter
period of time and therefore spend less time away from competition.

22. Rehabilitation and
Injury Prevention
Other forms of rehabilitation and injury prevention for
hamstring injuries include:
• Sports Massage
• Acupuncture
• Taping techniques
• Compression Shorts
• Bracing
•Yoga and Pilates

23. Literature Review
(Evidence based prevention of hamstring injuries in sport.
Petersen & Holmich, 2005)
• Age, physical status, type of sport, exercise techniques and warm-
up strategies are important elements used to predict the likelihood
of a hamstring injury.
• A lack of clinical evidence exists regarding the effectiveness of
hamstring rehabilitation methods. However immobilization
throughout the recovery phase of injury is known to have a negative
impact on healing (Morgan & Allen, 1999).
• There is a high incidence of recurring hamstring injuries especially
if inadequate rehabilitation and/or an appropriate warm-up is not
performed before physical activity.
• In the AFL, research suggests that each club experiences 5-6
hamstring related injuries per year. This amounts to 15-21 games
missed per season (Brockett, 2004).

24. Literature Review
• The biarticular arrangement of the hamstring muscle group
provides a substantial risk of injury especially due to poor
biomechanical techniques and/or muscle weakness.
• Studies suggest that the period of change from an eccentric to a
concentric contraction is most susceptible to strain injuries.
• Studies have shown that fatigue has a major influence regarding
injury risk. An investigation into English professional football
showed that a significant number of hamstring injuries occurred in
the latter stages of each half (Askling et.al, 2006).
• Hamstring strength , flexibility exercises and the presence of pain
should be used to determine when an athlete can return to
competition.

25. References
Askling, C., Saartok, T., & Thorstensson, A. (2006). Type of acute
hamstring strain affects flexibility, strength, and time to
return to pre-injury level. British Journal of Sports Medicine,
40(1):40-44.
Brockett, C., Morgan, D., & Proske, U. (2004). Predicting hamstring
strain injury in elite athletes. Medicine and Science in Sports
and Exercise, 36(3): 379-387.
Hoskins, W., & Pollard, H. (2005). The management of hamstring
injuries – part 1: Issues in diagnosis. Manual Therapy, 10(1):
96-107.
Malliaropoulos, N., Papalexandris, S., Papalada, A., & Papacostas, E.
(2004). The role of stretching in rehabilitation of hamstring
injuries: 80 athletes follow-up. Medicine and Science in Sports
and Exercise, 37(1): 756-759.

26. References
Morgan, D., & Allen, G. (1999). Early events in stretched-induced
muscle damage. Journal of Applied Physiology, 87(1): 2007-
2015.
Noonan, T., & Garrett, W. (1999). Muscle strain injury: Diagnosis and
treatment. Journal of American Academy of Orthopaedic
Surgery, 7(1): 262-269.
Orchard, J., Marsden, S., & Garlick, D. (1997). Preseason hamstring
muscle weakness associated with hamstring muscle injury in
Australian footballers. American Journal of Sport Medicine,
25(1):81-85.
Petersen, J., & Holmich, P. (2005). Evidence based prevention of
hamstring injuries in sport. British Journal of Sports Medicine,
39(1): 319-323.
Sports Injury Clinic. (2009). Hamstring Strain Rehabilitation. Retrieved
April 29, 2009, from
http://www.sportsinjuryclinic.net/cybertherapist/back/hams
trings/hamstringstrain.htm