Understanding Hamstrings in Football: Anatomy, function & rehabilitation

Despite their importance, hamstring injuries remain one of the most prevalent and recurring issues in the sport, with a significant impact on player availability and performance. Understanding the anatomy, function, and injury mechanisms of the hamstrings is essential for footballers, coaches, and medical teams striving to optimise performance and reduce risk of injury.

This article delves into the intricate anatomy of the hamstrings, the biomechanics behind their function, and the evidence-based strategies for managing and rehabilitating injuries. Whether you're a player looking to stay fit or a practitioner aiming to enhance your expertise, this comprehensive guide will equip you with the knowledge to address one of football’s most persistent challenges.

Let’s explore how a deeper understanding of the hamstrings can transform injury prevention, rehabilitation, and ultimately, on-field performance.

Anatomy of the hamstrings

The hamstring group consists of three large muscles (posterior thigh). The biceps femoris (BF) is found laterally, with the semimembranosus (SM) and semitendinosus (ST) found medially. The hamstrings are notable for the fact that they cross two joints and have long proximal (upper) and distal (lower) tendons with resultant long muscle tendon junctions that extend well into the muscle bellies. Their role is to facilitate transmission of forces across the muscle during muscle contraction and relaxation. The long hamstring tendons leads to a greater ‘‘spring’’ effect that enhances athletic performance yet increases injury risk. The interface between the muscle fibres and the relatively stiff tendon fibres is the weakest point of the muscle tendon unit (1).  

Hamstring muscle fibres are notable for containing a relatively large proportion of fast twitch fibres that enable a relatively short time to develop peak muscle tension, allowing faster muscle contractions.

The hamstrings originate from the ischial tuberosity. The BF is divided into two portions; long and short head. Long head originates as part of the joint tendon with semitendinosus with its fibres running down the lateral side of the knee. The short head arises from the shaft of the femur just below glute max and its fibres run downwards and insert into the lateral aspect of the knee (2).  The ST originates as part of the joint tendon with BF with its fibres running down and forming a long, thin lower tendon inserting into the upper part of the inside of the lower leg. The SM originates from the ischial tuberosity separate to the joint tendon of the BF and ST with its fibres attaching down into the medial aspect of the lower leg. 

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Function of Hamstrings 

The function of the hamstrings is to produce knee flexion and hip extension. Particularly during high speed running (HSR) and sprinting, one of the primary functions is to decelerate the lower limb through terminal swing phase. During sprinting the hamstrings undergo a stretch shortening cycle (SSC) with the stretch-eccentric phase occurring during terminal swing when the hip flexes and the knee extends. When reaching speeds of 7-9m/s the forces going through the hamstring complex range from 4.61-8.95xBW demonstrating the need for strong hamstrings (3). Additionally during terminal swing phase the long head BF has the largest peak muscle-tendon strain with ST displaying the greatest muscle-tendon lengthening velocity and SM producing the highest muscle-tendon force (4). At this stage we must also point out the ambiguity of the eccentric vs. isometric argument in sprinting for the hamstring muscles (5).

Injury Epidemiology 

Hamstring muscle injuries have increased in incidence in men’s professional football from 2001 to 2014. During eight seasons (14/15 to 21/22) the incidence and burden of hamstring injuries during both training and match play increased significantly.

Hamstring injury incidence has doubled from 12% in 01/02 season to 24% in 21/22.

With around 18% of all reported injuries being recurrences with over two-thirds occurring within 2 months of RTP. This is hugely costly not only to the players but also the clubs.

Common Mechanisms 

The player will often report a mechanism of sprinting. The most likely point of injury in these scenarios is either at late swing (6) when the hamstring muscles work to resist knee joint extension to decelerate the shank, or at initial ground contact in a closed chain position (7).

A stretching mechanism may also cause injury to the hamstring muscles, for example during a brake like action with a lunge or landing action as well as open chain movements like kicking or stretching (8). Research suggests that such injuries may require a longer rehabilitation time compared to sprint type injuries due to often involving the free proximal tendon of the SM (9). A full subjective history should be taken regarding the mechanism, and where possible be supported by video analysis.

In one systematic video analysis study of the two highest divisions in Germany over four seasons from 2014-2019 the most affected muscle was the bicep femoris (79%) (10).

Clinical Assessment 

Thorough clinical assessment is required post injury to determine extent and whether an MRI is required for full diagnosis. The following section details how our Sports Therapist would carry out a hamstring clinical assessment. 

Palpation

Palpation of the injured tissue is used to identify the exact location of pain, size and also the length of painful area. Research suggests that a 1cm increase in length of tenderness has been associated with 1-day increase in RTP time (11). 

Range of Motion

The maximal hip flexion active knee extension (MHFAKE) and straight leg raise (SLR) test’s are used predominantly to assess the muscle range of motion (ROM). Specifically with the MHFAKE; positive symptoms in this test have been associated with the progress of running speed during rehabilitation more than ASLR (12).

Strength

During the clinical assessment the players strength / force output can be assessed through bilateral and unilateral isometrics at various different ranges which can be completed in both supine and prone. Additionally bilateral and unilateral hamstring bridges can be used at different ranges to help identify areas of discomfort but also identify the specific injured tissue. If a supine 90-90 resisted knee flexion reproduces pain then this has been associated with a 4.7 day increased RTP time (13). 

If I pick up a hamstring injury - what may it feel like? 

The following section is based on clinical experience and provides you with some examples of what typically a hamstring injury may feel like in relation to the different grades. 

Grade 1

When a player has a grade 1 hamstring injury they often report a cramp like sensation and are able to complete the game or finish the training session. The player’s hamstring strength is unlikely to be significantly reduced but can sometimes be painful. Additionally their ROM can also be reduced. Finally, their subjective pain is often widespread and less focal compared to higher grades. 

Grade 2

Often with a grade 2 hamstring injury, players report a specific onset of pain which is likely during a sprint or stretch which typically leads to them being unable to continue training or needing to be removed from play during a game. They also report a focal point of pain on palpation which is coupled with reduced strength and ROM during the clinical assessment. 

Grade 3-4

A grade 3 or grade 4 hamstring injury typically takes an extended period of time to recover in comparison to lesser grades. The majority but not all of higher grade hamstring injuries have a specific mechanism again typically during sprinting and are unable to finish the game or training session. There is quite often a focal point of pain on palpation, typically at tendon with some injuries presenting with an observable/palpable retraction of muscle in prone knee flexion. The SLR often has a reduced range or even increased if there is a complete loss of tension. Pain could be very high or absent on testing. 

Adverse Features on Scans 

The gold standard testing for a hamstring injury to determine the extent of the injury is an MRI. Following an MRI the images will be reported on by a consultant radiologist. MRI’s are used to identify injured structures. MRI sensitivity for hamstring injuries when clinical testing is positive is approximately 70-90%, therefore 10-30% of cases where the player is symptomatic will be a grade 0 (14). There can be adverse features reported which can alter the return to play times. Some adverse features can be seen below:

Free tendon

Free tendon injuries require early detection and surgical review. Surgical repair of a tendon avulsion should be completed as soon as possible to promote optimal outcomes due to the scarring of the sciatic nerve around the avulsed tissue can be problematic if left.

Intramuscular tendon

Intramuscular (IM) tendon involvement is often associated with longer return to play (RTP) time (14). Often these injuries present well clinically and function well in rehab at sub-max intensities but when reaching higher intensity sessions these can be problematic, meaning there needs to be caution taken when exposing the player to higher velocity running. 

Length of Oedema

Length of oedema has been shown to have a greater association with RTP times in comparison to cross sectional area (CSA) in AFL hamstring injuries (15). 

Distal BF T-junction

The distal musculotendinous junction between BF SH & LH is referred to as the T-junction which is associated with a high recurrence rate (16). This may be due to the site traditionally classified as a myofascial injury and therefore the healing time and load progressions which are required may have been under-appreciated. Furthermore, the complex distal anatomy along with the dual innervation of the SH & LH could possibly be complicating factors.

Neural Involvement

The sciatic nerve innervates the hamstring muscle group which should be assessed in slump and/or SLR testing as part of clinical assessment. Further testing/imaging could be considered of the lumbar spine if positive tests/re-occurring hamstring injuries. 

Timeframes 

The table below outlines the mean time to return to full training in days, range and injury recurrence rate in hamstring injuries using BAMIC system - (17)

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Interestingly, our incredibly successful hamstring rehab case study with Alex Oxlade-Chamberlain between January and March 2024 lasted a total of 93 days. This injury was a 4c distal t-junction repair, and saw Alex check-out of rehab at all-time physical highs! 

Risk Factors for Hamstring Injury 

Previous injury

Within the research it is widely acknowledged that the greatest risk factor for injury is previous injury (18). 

Self-reporting risk factors

Some players subjectively self-report risk factors that may be linked to the incidence of hamstring injuries; Low back pain/stiffness, hamstring DOMS, prolonged sitting

Objective risk factors

Objective risk factors which can be assessed and monitored throughout the rehabilitation process to guide the process are; Hamstring ROM, global ROM specifically at spine and hips, lumbo-pelvic control, intramuscular coordination, hip extension strength, knee flexor strength and then finally GPS ensuring the player is getting exposed to their individual metrics prior to RTP. 

Other risk factors

Other risk factors for hamstring injuries are; Increasing age, fatigue, dehydration, sleep and stress. 

Return to play criteria

Rehab Considerations / Injury Prevention Work 

Since 17% of all muscle injuries are recurrences, an ongoing management plan is essential (19). This also means that the rehabilitation plan needs to be individualised and data driven to reduce re-injury risk. Ultimately the program needs to promote the ability of hamstrings to deal with lengthening forces at hip and knee joints at different speeds whilst shifting the angle of peak torque towards outer range.

Specific loading

Being specific with targeting certain muscles/location depending on scan report/injury. For example, Nordics will target more medial distal hamstrings compared to RDL’s more proximal, wide foot leg press to target SM and adductor magnus. 

Rate of Force Development (RFD)

Rate at which hamstrings can produce force is important due to the requirement to produce maximal force quickly during actions such as sprinting, accelerating and decelerating (20). Neural components contribute mostly to early RFD (0-75ms) but in later stages (75-200ms) the force is determined by more contractile components of the muscle (21) – highlighting the importance of using tech to guide rehab progressions and to be used once player is fit to reduce risk of re-injury. RFD often takes longer to return in an injured muscle compared to achievement of strength (22). Rehab/S&C work needs to challenge muscle tendon unit to work across the full length of the force-velocity curve.

Endurance

It has been shown that ST provides an endurance capacity in hamstring activity and once fatigued increases the reliance on the BF (23). Hamstring injuries often happen towards the end of a game or training session likely when fatigue is high so therefore potentially demonstrating a reasoning behind endurance-based work during the acute/general prep phase of rehab. 

Eccentric strength

Shorter fascicle lengths have been associated with higher risk of hamstring injury in footballers (24).  Fascicle lengths can be altered through consistent exposure to eccentrics by increasing sarcomeres in sequence (25). Lower incidence of hamstring injuries has been reported in athletes who complete high load eccentric training along with improving the angle of peak torque production (26; 27). 

Isometrics

Can be used in the initial phase of rehabilitation to improve motor unit recruitment before exposing injured tissue to higher intensity exercises in the gym. Isometrics are also important in tendon-based injuries to help increase tendon stiffness and initial force production. A further benefit of isometrics are that they can help improve fatigue resistance. 

Movement / Lumbo Pelvic control

Important for players to be strong through the trunk to ensure when running at high speeds, optimal proximal stability is provided for hamstring force production. Deficiencies in trunk control/strength have been associated with increased risk of hamstring injury (28). 

Running Program

High speed running produces higher activation of the hamstring muscle group compared to gym based exercises (29). Therefore a graded exposure to high speed running (HSR) and also max velocity sprinting during rehab is essential – volume, frequency and intensity needs to be correctly programmed in order to reduce re-injury risk. The prescribed distance of sprinting should also be carefully planned when exposing players to max sprint distances as it takes up to 40 m to reach a max velocity during a max effort (30). However, our experience guides us that football athletes actually reach max velocity earlier than 30 m due to their greater accelerative vs. max velocity capabilities. Ensuring players once fit are being regularly exposed to 90%+ max velocity running is essential.

Reference List

1. Linklater, J. M., Hamilton, B., Carmichael, J., Orchard, J., & Wood, D. G. (2010). Hamstring injuries: Anatomy, imaging, and intervention. Seminars in Musculoskeletal Radiology, 14(2), 131–161.
2. Linklater, J. M., Hamilton, B., Carmichael, J., Orchard, J., & Wood, D. G. (2010). Hamstring injuries: Anatomy, imaging, and intervention. Seminars in Musculoskeletal Radiology, 14(2), 131–161.
3. Dorn, T. W., Schache, A. G., & Pandy, M. G. (2012). Muscular strategy shift in human running: Dependence of running speed on hip and ankle muscle performance. The Journal of Experimental Biology, 215(Pt 11), 1944–1956. 
4. Schache, A. G., Dorn, T. W., Blanch, P. D., Brown, N. A. T., & Pandy, M. G. (2012). Mechanics of the human hamstring muscles during sprinting. Medicine and Science in Sports and Exercise, 44(4), 647–658. 
5. Van Hooren, B., & Bosch, F. (2017). Is there really an eccentric action of the hamstrings during the swing phase of high-speed running? part I: A critical review of the literature. Journal of sports sciences, 35(23), 2313–2321.
6. Chumanov, E., Schache, A., Heidersheit, B., and Thelen, D. (2012). Hamstrings are most susceptible to injury during the late swing phase of sprinting . BJSM, 46(90).
7. Orchard, J., Driscoll, T., Seward, H., and Orchard, J. (2012). Relationship between interchange usage and risk of hamstring injuries in the Australian Football League. Journal of Science and Medicine in Sport, 15(3), 201-206. 
8. Gronwald, T., Klein, C., Hoenig, T., Pietzonka, M., Bloch, H., Edouard, P., & Hollander, K. (2022). Hamstring injury patterns in professional male football (Soccer): A systematic video analysis of 52 cases. British Journal of Sports Medicine, 56(3), 165–171. 
9. Askling, C. M., Malliaropoulos, N., & Karlsson, J. (2012). High-speed running type or stretching-type of hamstring injuries makes a difference to treatment and prognosis. British Journal of Sports Medicine, 46(2), 86–87. 
10. Gronwald, T., Klein, C., Hoenig, T., Pietzonka, M., Bloch, H., Edouard, P., & Hollander, K. (2022). Hamstring injury patterns in professional male football (Soccer): A systematic video analysis of 52 cases. British Journal of Sports Medicine, 56(3), 165–171. 
11. Wangensteen, A., Almusa, E., Boukarroum, S., Farooq, A., Hamilton, B., Whiteley, R., Bahr, R., & Tol, J. L. (2015). MRI does not add value over and above patient history and clinical examination in predicting time to return to sport after acute hamstring injuries: A prospective cohort of 180 male athletes. British Journal of Sports Medicine, 49(24), 1579–1587.  
12. Whiteley, R., van Dyk, N., Wangensteen, A., & Hansen, C. (2018). Clinical implications from daily physiotherapy examination of 131 acute hamstring injuries and their association with running speed and rehabilitation progression. British Journal of Sports Medicine, 52(5), 303–310. 
13. Wangensteen, A., Almusa, E., Boukarroum, S., Farooq, A., Hamilton, B., Whiteley, R., Bahr, R., & Tol, J. L. (2015). MRI does not add value over and above patient history and clinical examination in predicting time to return to sport after acute hamstring injuries: A prospective cohort of 180 male athletes. British Journal of Sports Medicine, 49(24), 1579–1587.  
14. van der Made, A. D., Almusa, E., Whiteley, R., Hamilton, B., Eirale, C., van Hellemondt, F., & Tol, J. L. (2018). Intramuscular tendon involvement on MRI has limited value for predicting time to return to play following acute hamstring injury. British Journal of Sports Medicine, 52(2), 83–88.
15.  Gibbs, N. J., Cross, T. M., Cameron, M., & Houang, M. T. (2004). The accuracy of MRI in predicting recovery and recurrence of acute grade one hamstring muscle strains within the same season in Australian Rules football players. Journal of Science and Medicine in Sport, 7(2), 248–258.
16.  Entwisle, T., Ling, Y., Splatt, A., Brukner, P., & Connell, D. (2017). Distal musculotendinous t junction injuries of the biceps femoris: An mri case review. Orthopaedic Journal of Sports Medicine, 5(7), 2325967117714998. 
17. Pollock, N., Patel, A., Chakraverty, J., Suokas, A., James, S. L. J., & Chakraverty, R. (2016). Time to return to full training is delayed and recurrence rate is higher in intratendinous ('C’) acute hamstring injury in elite track and field athletes: Clinical application of the British Athletics Muscle Injury Classification. British Journal of Sports Medicine, 50(5), 305–310.
18. Freckleton, G., Cook, J., & Pizzari, T. (2014). The predictive validity of a single leg bridge test for hamstring injuries in Australian Rules Football Players. British Journal of Sports Medicine, 48(8), 713–717.
19. Hägglund, M., Waldén, M., Bengtsson, H., & Ekstrand, J. (2018). Re-injuries in professional football: The uefa elite club injury study. In V. Musahl, J. Karlsson, W. Krutsch, B. R. Mandelbaum, J. Espregueira-Mendes, & P. d’Hooghe (Eds.), Return to Play in Football: An Evidence-based Approach (pp. 953–962). Springer. 
20. Wilson, G. J., Lyttle, A. D., Ostrowski, K. J., & Murphy, A. J. (1995). Assessing dynamic performance: A comparison of rate of force development tests. The Journal of Strength and Conditioning Research, 9(3), 176. 
21. Grindstaff, T. L., Palimenio, M. R., Franco, M., Anderson, D., Bagwell, J. J., & Katsavelis, D. (2019). Optimizing between-session reliability for quadriceps peak torque and rate of torque development measures. Journal of Strength and Conditioning Research, 33(7), 1840–1847. 
22. Taberner, M., Allen, T., & Cohen, D. D. (2019). Progressing rehabilitation after injury: Consider the ‘control-chaos continuum’. British Journal of Sports Medicine, 53(18), 1132–1136.
23. Schuermans, J., Van Tiggelen, D., Palmans, T., Danneels, L., & Witvrouw, E. (2017). Deviating running kinematics and hamstring injury susceptibility in male soccer players: Cause or consequence? Gait & Posture, 57, 270–277. 
24. Timmins, R. G., Bourne, M. N., Shield, A. J., Williams, M. D., Lorenzen, C., & Opar, D. A. (2016). Short biceps femoris fascicles and eccentric knee flexor weakness increase the risk of hamstring injury in elite football (Soccer): A prospective cohort study. British Journal of Sports Medicine, 50(24), 1524–1535.
25. Timmins, R. G., Ruddy, J. D., Presland, J., Maniar, N., Shield, A. J., Williams, M. D., & Opar, D. A. (2016). Architectural changes of the biceps femoris long head after concentric or eccentric training. Medicine and Science in Sports and Exercise, 48(3), 499–508. 
26. Askling, C. M., Malliaropoulos, N., & Karlsson, J. (2012). High-speed running type or stretching-type of hamstring injuries makes a difference to treatment and prognosis. British Journal of Sports Medicine, 46(2), 86–87. 
27. Brughelli, M., Cronin, J., Mendiguchia, J., Kinsella, D., & Nosaka, K. (2010). Contralateral leg deficits in kinetic and kinematic variables during running in Australian rules football players with previous hamstring injuries. Journal of Strength and Conditioning Research, 24(9), 2539–2544. 
28. Schuermans, J., Van Tiggelen, D., Palmans, T., Danneels, L., & Witvrouw, E. (2017). Deviating running kinematics and hamstring injury susceptibility in male soccer players: Cause or consequence? Gait & Posture, 57, 270–277. 
29. van den Tillaar, R., Solheim, J. A. B., & Bencke, J. (2017). Comparison of hamstring muscle activation during high-speed running and various hamstring strengthening exercises. International Journal of Sports Physical Therapy, 12(5), 718–727.
30. Debaere, S., Jonkers, I., & Delecluse, C. (2013). The contribution of step characteristics to sprint running performance in high-level male and female athletes. Journal of Strength and Conditioning Research, 27(1), 116–124.