Hamstring Strain

Injuries3003PES – Injury Prevention and Management

By DION OBST

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

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://mm.afl.com.au/Source: http://www.fotosearch.com/

DefinitionsA 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

AetiologyHamstring strain injuries are graded according to their severity:

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.

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

Aetiology

The most common causal factors of 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

Normal

Great flexibility

Anatomy of the

HamstringThe hamstring comprises of 3 major muscles:

1) Biceps Femoris (long and short head)

2) Semitendinosis3) Semimembranosis

The hamstrings span over two joints - the hip and the knee joint

(Hoskins & Pollard, 2005)

Muscle

Origin Insertion

1. (long)

Ischial Tuberosity

Head of Fibula (lateral side)

(short)

Linea Aspera Head of Fibula (lateral side)

2. Ischial Tuberosity

Tibia (medial surface)

3. Ischial Tuberosity

Tibial Condyle (medial)Source: http://www.fotosearch.com/

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).

• 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).

Muscle Physiology

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 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/

Source: https://console.clubsonline.com.au/

Biomechanics of the

HamstringThe 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/

Biomechanics of the

Hamstring During gait, injuries most commonly occur at the end stage of the swing phase (Hoskins & Pollard, 2005).

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.

MUSCLE ACTION

Semitendinosis/Semitendinosis

Predominantly involved in hip extension. Also knee flexion and internal rotation of lower leg.

Biceps Femoris (long)

Hip extension at beginning of gait cycle

Biceps Femoris (Long & Short Head)

Knee flexion and external rotation of the lower leg.

Biomechanics of the

HamstringA 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)

Mechanisms of InjuryThe 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).

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/

Clinical DiagnosisThe 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.

Resisted Knee Flexion – Passive resistance as patient bends knee.Causes hamstring contraction and painStrength of movement is compared to opposite limb

(http://www.sportsinjuryclinic.net/)

Source: http://bjsm.bmj.com/

Source: http:// http://www.chiroandosteo.com/

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.

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://www.ihcatl.com/

Source: http://thump01.pbase.com/

Differential 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/

Source: http://www.fotosearch.com/

Phases of Injury and TreatmentThe following table summarises the 5 phases of injury

proposed by Petersen & Holmich (2005) and the appropriate actions to aid recoveryPhases of Injury Signs/treatment

Phase 1 (acute): 1 - 7days

• RICER treatment is importantGoal: Minimise swelling, pain and control haemorrhaging.• Use of NSAIDs for short period after injury.• Light movement techniques prevent adhesions.

Phase 2 (subacute): 3days – 3weeks

• Inflammatory symptoms begin to resolve.• Basic exercise techniques promote healing and prevent muscle atrophy. Concentric exercises introduced.• Cardiovascular fitness should be maintained.

Phase 3 (remodelling): 1 – 6 weeks

• Loss of flexibility due to scar tissue formation and pain.• Stretching performed to maintain flexibility.• Eccentric exercise introduced (light to avoid re-injury)

Phase 4 (functional): 2wks – 6months

Goal: Decrease the risk of re-injury during sport.• Sport specific strength and flexibility protocols initiated.

Phase 5 (return to comp): 3wks – 6mths

Goal: Maintain strength and flexibility of muscle to avoid recurring injury.

RehabilitationOnce 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 STRETCHINGInternal rotation

External rotation

CONTRACT – RELAX STRETCHING

DYNAMIC STRETCHING

Swinging of leg forward and backwards with gradual increases in height

Source:(http://www.sportsinjuryclinic.net/)

RehabilitationA 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.

Rehabilitation and Injury PreventionOther forms of rehabilitation and injury

prevention for hamstring injuries include:

• Sports Massage

• Acupuncture

• Taping techniques

• Compression Shorts

• Bracing

• Yoga and Pilates

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).

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.

ReferencesAskling, 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.

ReferencesMorgan, 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/hamstrings/hamstringstrain.htm