Hamstring Strain Rehabilitation: A Comprehensive Review of Current Best Practices

Hamstring strain injuries (HSIs) are common among athletes, especially those participating in sports that involve sprinting, sudden acceleration and deceleration, change of direction, and kicking. These injuries often result in significant time lost from sport and have a high rate of recurrence1. Effective rehabilitation is crucial for restoring function, minimizing reinjury risk, and optimizing return to sport (RTS). This comprehensive review examines current best practices for hamstring strain rehabilitation, encompassing exercise protocols, manual therapy techniques, and strategies for a safe and successful RTS.

Understanding Hamstring Strain Injuries

Anatomy and Function

The hamstring muscle group is a collection of three muscles situated at the back of the thigh, originating from the ischial tuberosity and extending to the lower leg. These muscles include the biceps femoris (with its long and short heads), semimembranosus, and semitendinosus. They are essential for movements such as extending the hip and flexing the knee, playing a crucial role in activities like running, jumping, and kicking2.

Mechanisms of Injury

HSIs typically occur from a complex interplay of factors, often involving:

  1. High muscle-tendon unit forces: Excessive force during muscle contraction or stretching can overwhelm the tissue's capacity, leading to a strain4.
  2. Extensive muscle-tendon unit lengthening: When the hamstring is stretched beyond its normal range, particularly during high-speed activities, the risk of injury increases4. This is especially relevant during the swing phase of running, where the hamstrings reach their maximum length and generate peak tension to decelerate hip flexion and knee extension5.
  3. High-velocity movements: Rapid acceleration, deceleration, and changes in direction can impose significant stress on the hamstrings, increasing their susceptibility to strains4. Research indicates that the hamstrings are subjected to greater stretch and faster speeds during acceleration from lower running speeds compared to maintaining a constant top speed6. This may explain why hamstring strains frequently occur during acceleration phases.
  4. Neuromuscular factors: A breakdown in coordination between the hamstrings and quadriceps, particularly during the late swing phase of running, can contribute to hamstring strains5. This highlights the importance of neuromuscular control in injury prevention and rehabilitation.

Risk Factors

Several factors can elevate the risk of HSIs:

  1. Older age: With age, muscle elasticity and the capacity for tissue repair diminish5.
  2. Previous hamstring injury: A history of hamstring strains increases the likelihood of future injuries2.
  3. Limited hamstring flexibility: While not a primary risk factor, reduced flexibility may contribute to injury in some cases5.
  4. Increased fatigue: Fatigued muscles are more prone to strains5.
  5. Poor core stability: Weakness in the core muscles can compromise pelvic control and increase the strain on the hamstrings5.
  6. Strength imbalance: Imbalances between hamstring and quadriceps strength can heighten the risk of injury5. This imbalance can disrupt the coordinated muscle activation needed for efficient movement and injury prevention.

Clinical Examination

A thorough clinical examination is crucial for assessing hamstring strain injuries. This examination typically includes:

  1. Palpation: Assessing for tenderness and identifying the location and extent of the injury.

  2. Range of motion: Evaluating active and passive range of motion in the hip and knee to determine any limitations or pain provocation.

  3. Strength testing: Assessing hamstring muscle strength through manual muscle testing or using a handheld dynamometer8. Isokinetic dynamometers can also be used to provide more objective and quantifiable measures of strength.

  4. Special tests: Performing specific clinical tests to assess the integrity of the hamstring muscles and differentiate between different types of injuries. Some commonly used tests include: 5

  5. Puranen-Orava test: Actively stretching the hamstrings with the hip flexed and knee extended.

    1. Bent-Knee stretch test: Assessing hamstring flexibility with the knee bent.
    2. Modified Bent-knee stretch test: A variation of the Bent-Knee stretch test.
    3. Taking off the shoe test/hamstring-drag test: Evaluating hamstring function during a simulated movement.

Rehabilitation of Hamstring Strain Injuries

General Principles

The primary goals of hamstring strain rehabilitation are to:

  1. Promote healing: Facilitate tissue repair and regeneration.
  2. Restore function: Regain full range of motion, strength, and flexibility.
  3. Minimize reinjury risk: Address underlying factors and implement preventive strategies.
  4. Optimize RTS: Enable a safe and successful return to sports participation5.

Rehabilitation Phases

Hamstring strain rehabilitation typically progresses through distinct phases, each with specific goals and interventions:

Phase 1: Pain Management and Early Motion (0-3 weeks) 9

  1. Goals: Protect healing tissue, minimize pain and swelling, and prevent muscle atrophy and stiffness.

  2. Interventions:

  3. Protection: Avoid activities that exacerbate pain9.

    1. Pain management: RICE (rest, ice, compression, elevation), modalities (e.g., electrical stimulation, ultrasound), and pain medication as needed9.
    2. Early motion: Gentle range of motion exercises to maintain flexibility and promote circulation9.
    3. Manual therapy: Soft tissue mobilization to reduce muscle tension and improve blood flow10.

Phase 2: Strengthening and Neuromuscular Control (3-12 weeks) 9

  1. Goals: Increase hamstring strength, improve neuromuscular control, and progress towards functional activities. Once the initial pain and swelling have subsided (Phase 1), rehabilitation progresses to strengthening and neuromuscular control (Phase 2).

  2. Interventions:

  3. Progressive strengthening: Start with isometric exercises and gradually progress to concentric and eccentric exercises9. Knee flexor strength can be objectively measured using handheld or isokinetic dynamometers8.

    1. Neuromuscular control: Exercises to improve balance, coordination, and proprioception9.
    2. Manual therapy: Continue soft tissue mobilization and joint mobilization to address restrictions9.

Phase 3: Advanced Strengthening and Functional Progression (4-8 weeks) 14

  1. Goals: Further increase strength and power, improve dynamic stability, and progress towards sport-specific activities. With improved strength and neuromuscular control (Phase 2), the focus shifts to advanced strengthening and functional progression (Phase 3).

  2. Interventions:

  3. Advanced strengthening: Incorporate higher-level exercises, including plyometrics and eccentric exercises at longer muscle lengths14.

    1. Functional progression: Introduce activities that simulate sport-specific movements14.
    2. Manual therapy: Address any remaining restrictions and optimize biomechanics14.

Phase 4: Return to Sport (8-12 weeks) 14

  1. Goals: Achieve full pain-free function, demonstrate sport-specific skills, and safely return to competition. Building upon the foundation of strength, stability, and functional capacity (Phase 3), the emphasis transitions to a safe and effective return to sport (Phase 4).

  2. Interventions:

  3. Sport-specific training: Gradual reintegration into full training activities14.

    1. Performance monitoring: Assess readiness for RTS using objective measures14.
    2. Injury prevention strategies: Implement strategies to minimize reinjury risk14.

Phase 5: Unrestricted Return to Sport (12+ weeks) 14

  1. Goals: Maintain fitness, prevent reinjury, and optimize long-term athletic performance. Following a successful return to sport (Phase 4), the focus shifts to maintaining fitness and preventing future injuries (Phase 5).

  2. Interventions:

  3. Full participation in training and competition. 14

    1. Ongoing strength and conditioning. 14
    2. Continued injury prevention strategies. 14

Exercise Protocols

Effective exercise protocols are essential for hamstring strain rehabilitation. Key considerations include:

  1. Progressive overload: Gradually increase the intensity, volume, and complexity of exercises as the injury heals13.
  2. Eccentric training: Emphasize eccentric exercises, which involve controlled lengthening of the muscle, to improve strength and resilience13.
  3. Functional exercises: Incorporate exercises that mimic sport-specific movements to enhance functional capacity13.
  4. Pain monitoring: Progress exercises within pain tolerance limits, avoiding excessive pain15. Pain should be monitored throughout the rehabilitation process. While some discomfort may be expected, exercises should not exacerbate pain or cause significant increases in pain levels. If pain persists or worsens, the exercise should be modified or stopped.
  5. Individualized approach: Recognize that different hamstring muscles have distinct functional roles and anatomical characteristics15. Rehabilitation exercises should be tailored to address the specific needs of the individual and the injured muscle(s).
  6. Long-term training: Nordic hamstring exercises (NHE) have been shown to induce significant adaptations in hamstring muscle structure, but these adaptations require consistent, long-term training6. Short blocks of NHE may not be sufficient to achieve lasting benefits. Microendoscopy studies have provided valuable insights into these muscle adaptations at a microscopic level6.

Examples of Hamstring Exercises:

Exercise Category Level 1 Level 2 Level 3
Knee Flexion Strength Isometric hamstring curls (prone) 16 Hamstring curls with gym ball or heel slides 16 Hamstring curls with weight or resistance band 16
Hip Extension Strength Bodyweight single-leg Romanian deadlift (RDL) 17 Weighted single-leg RDL 17 Weighted RDL (both legs) 17
Hip Extension Strength 45-degree hip extension (Roman chair or back extension machine) 17 Single-leg 45-degree hip extension 17 Weighted single-leg hip extension 17
Hip Extension Strength Hamstring bridge (feet on elevated surface) 17 Eccentric hamstring bridge (lower one leg at a time) 17 Single-leg hamstring bridge 17
Eccentric Strength Eccentric hamstring sliders (double leg) 13 Single-leg eccentric sliders 13 Nordic hamstring curls 13

Manual Therapy Techniques

Manual therapy can be a valuable adjunct to exercise in hamstring strain rehabilitation. Techniques commonly used include:

  1. Soft tissue mobilization: Hands-on techniques to address muscle tension, trigger points, and fascial restrictions10. These techniques can be applied to specific areas of the hamstring muscles, such as the biceps femoris, to improve mobility and reduce pain18.
  2. Joint mobilization: Techniques to restore joint mobility and improve biomechanics10.
  3. Neural mobilization: Techniques to address nerve tension and improve nerve gliding14.

Optimizing Return to Sport

A successful RTS requires a comprehensive approach that considers various factors:

  1. Time: Adequate healing time is crucial, and premature RTS increases reinjury risk19. Returning to running and sprinting too early can hinder healing and increase the risk of re-injury20. A structured and progressive return to high-speed running and sprinting is essential21.
  2. Pain: Athletes should be pain-free during all activities before returning to sport15.
  3. Strength and flexibility: Restore hamstring strength and flexibility to pre-injury levels15. Restoring optimal hamstring length and flexibility is crucial for regaining full function and preventing future injuries22.
  4. Functional capacity: Demonstrate the ability to perform sport-specific movements without limitations15.
  5. Psychological readiness: Address any fear or anxiety related to reinjury14.
  6. Monitoring and technology: Experts recommend using global positioning systems (GPS) and other technology to monitor athletes' loading and running dosages during rehabilitation15. This data can help guide training progression and ensure a safe RTS.

Criteria for Return to Play:

  1. Full range of motion and flexibility.
  2. Symmetrical strength compared to the uninjured leg.
  3. Pain-free performance of sport-specific movements at full speed and intensity.
  4. Completion of a progressive RTS testing battery.
  5. Psychological readiness and confidence in the injured leg.

It is important to note that athletes have a significant chance of re-injury after a hamstring strain, often due to insufficient rehabilitation or premature return to play23. A recent study showed that individuals recovering from hamstring strains who performed exercises with up to 4/10 pain demonstrated improved hamstring strength compared to those who only performed pain-free exercises23. This suggests that a pain-threshold approach to rehabilitation may be beneficial.

Recent Research

Several recent studies have provided valuable insights into hamstring strain rehabilitation:

  1. A randomized controlled trial comparing early versus delayed introduction of lengthening exercises in hamstring rehabilitation found no significant difference in time to return to sport or reinjury rates between the two groups19. This suggests that accelerating the introduction of lengthening exercises may not necessarily improve outcomes.
  2. A study comparing pain-free versus pain-threshold rehabilitation for hamstring strains found that pain-threshold rehabilitation did not accelerate return to play but resulted in greater recovery of isometric knee flexor strength and better maintenance of biceps femoris long head fascicle length24. This supports the notion that a pain-threshold approach may be beneficial in rehabilitation.
  3. A meta-analysis on the efficacy of rehabilitation exercises and platelet-rich plasma injections for hamstring injuries showed that rehabilitation exercises significantly reduced time to return to play, while platelet-rich plasma injections had no significant effect25. This reinforces the importance of exercise-based rehabilitation for hamstring strains.
  4. A study comparing return to participation time after hamstring strains in male and female collegiate soccer players found no significant difference in return to play time between sexes for first-time strains26. However, the study identified some sex-specific factors that may influence recovery.

Injury Prevention Strategies

Implementing injury prevention strategies is crucial to minimize the risk of recurrent hamstring strains. These strategies include:

  1. Warm-up: Adequate warm-up before activity prepares the muscles for the demands of sport2. This should include at least 10 minutes of light activity, such as jogging or calisthenics, followed by 3-5 minutes of dynamic stretching2.
  2. Stretching: Regular stretching, including dynamic stretching before activity and static stretching after, can help maintain flexibility2.
  3. Strength and conditioning: A comprehensive strength and conditioning program that includes exercises for the hamstrings, quadriceps, and core muscles is essential2. This program should be tailored to the specific demands of the athlete's sport and position26.
  4. Neuromuscular control: Exercises to improve balance, coordination, and proprioception can enhance movement efficiency and reduce injury risk2.
  5. Load management: Avoid excessive training volume and intensity, and allow for adequate rest and recovery29. Rest is crucial for muscle repair and rebuilding, and inadequate rest can increase the risk of fatigue-related injuries28.

Conclusion

Hamstring strain rehabilitation is a multifaceted process that requires a comprehensive and individualized approach. Effective rehabilitation programs incorporate evidence-based exercise protocols, manual therapy techniques, and strategies for optimizing return to sport. Current best practices emphasize the importance of:

  1. Progressive loading: Gradually increasing the demands placed on the hamstring muscles as they heal.
  2. Eccentric training: Incorporating exercises that involve controlled lengthening of the hamstrings to improve strength and resilience.
  3. Functional exercises: Including exercises that mimic the demands of the athlete's sport to enhance functional capacity.
  4. Pain monitoring: Progressing exercises within pain tolerance limits and avoiding excessive pain.
  5. Manual therapy: Utilizing hands-on techniques to address muscle tension, joint restrictions, and nerve mobility.
  6. Individualized treatment: Tailoring rehabilitation plans to the specific needs of the athlete and the injured muscle(s).
  7. Technology and monitoring: Utilizing tools like GPS to monitor training load and assess return to sport readiness.
  8. Injury prevention strategies: Implementing strategies to minimize the risk of recurrent hamstring strains.

By adhering to these best practices, clinicians can help athletes effectively recover from hamstring strains, minimize reinjury risk, and achieve a safe and successful return to sport. The evolving understanding of pain in rehabilitation, the importance of individualized treatment plans, and the role of technology in optimizing recovery and preventing reinjury are key takeaways for both clinicians and athletes.

Works cited

1. www.natafoundation.org, accessed February 17, 2025, /images/press/uploads/RTCP-Hamstring_Oct2022.pdf

2. Hamstring Injury: Treatment, Prevention & Recovery - Cleveland Clinic, accessed February 17, 2025, https://my.clevelandclinic.org/health/diseases/17039-hamstring-injury

3. Hamstring strain - Fit to Play, accessed February 17, 2025, https://fittoplay.org/body-parts/hamstring/-hamstring-strain-pulled-hamstringnew-page/

4. Hamstring Strain Injury Rehabilitation - PMC, accessed February 17, 2025, https://pmc.ncbi.nlm.nih.gov/articles/PMC8876884/

5. Hamstring Strain - Physiopedia, accessed February 17, 2025, https://www.physio-pedia.com/Hamstring_Strain

6. Innovative techniques shed light on hamstring injury in athletes ..., accessed February 17, 2025, https://news.stanford.edu/stories/2024/10/innovative-techniques-shed-light-on-hamstring-injury-in-athletes

7. Hamstring injury - Symptoms and causes - Mayo Clinic, accessed February 17, 2025, https://www.mayoclinic.org/diseases-conditions/hamstring-injury/symptoms-causes/syc-20372985

8. Hamstring Strain Guidelines: Guidelines Summary, accessed February 17, 2025, https://emedicine.medscape.com/article/307765-guidelines

9. Hamstring Strain Injuries: Recommendations for Diagnosis ..., accessed February 17, 2025, https://pmc.ncbi.nlm.nih.gov/articles/PMC2867336/

10. Recovering from Hamstring Strains: Rehabilitation Exercises and ..., accessed February 17, 2025, https://twinboro.com/recovering-from-hamstring-strains-rehabilitation-exercises-and-progressions-nj.html

11. Hamstring Strain Exercises to Heal a Strain FAST! | Petersen ..., accessed February 17, 2025, https://petersenpt.com/hamstring-strain-exercises-to-heal-a-strain-fast

12. Physical Therapy in Ashburn for Hamstring Pain, accessed February 17, 2025, https://www.ptbyart.com/Injuries-Conditions/Hamstring/Hamstring-Injuries/a~322/article.html

13. Hamstring Strain Rehab (Science-Based Strength and Running ..., accessed February 17, 2025,

14. www.massgeneral.org, accessed February 17, 2025, https://www.massgeneral.org/assets/MGH/pdf/orthopaedics/sports-medicine/physical-therapy/rehabilitation-protocol-for-hamstring-injury-non-operative.pdf

15. London International Consensus and Delphi study on hamstring injuries part 3: rehabilitation, running and return to sport, accessed February 17, 2025, https://bjsm.bmj.com/content/57/5/278

16. Exercises for Hamstring Strains | Expert Physio Top Tips - YouTube, accessed February 17, 2025,

17. Hamstring Strain Rehab & Exercises (Strength | Running | Return to Sport) - YouTube, accessed February 17, 2025,

18. Best way to treat the Hamstrings using a variety of Soft Tissue ..., accessed February 17, 2025,

19. Early versus delayed lengthening exercises for acute hamstring injury in male athletes: a randomised controlled clinical trial, accessed February 17, 2025, https://bjsm.bmj.com/content/56/14/792

20. Hamstring injury: treatment, recovery time and when to see a doctor ..., accessed February 17, 2025, https://iseh.co.uk/news/latest-news/hamstring-injury-treatment-recovery-time-and-when-to-see-a-doctor

21. Hamstring Strain Injury Rehabilitation | Journal of Athletic Training - Allen Press, accessed February 17, 2025, https://meridian.allenpress.com/jat/article/57/2/125/466426/Hamstring-Strain-Injury-Rehabilitation

22. Regaining Your Athletic Potential After a Hamstring Injury, accessed February 17, 2025, https://velocityspusa.com/hamstring-hero-regaining-your-athletic-potential-after-a-hamstring-injury/

23. When can I return to Sports After a Hamstring strain? | Athletic ..., accessed February 17, 2025, https://ptadvantage.com/when-can-i-return-to-sports-after-a-hamstring-strain/

24. Pain-Free Versus Pain-Threshold Rehabilitation Following Acute ..., accessed February 17, 2025, https://www.jospt.org/doi/10.2519/jospt.2020.8895

25. Efficacy of rehabilitation (lengthening) exercises, platelet-rich ..., accessed February 17, 2025, https://pubmed.ncbi.nlm.nih.gov/26198389/

26. Researchers Report on Return to Participation After Hamstring Strains Among College Soccer Athletes | NATA, accessed February 17, 2025, https://www.nata.org/press-release/072215/researchers-report-return-participation-after-hamstring-strains-among-college

27. joshuaharrismd.com, accessed February 17, 2025, https://joshuaharrismd.com/how-to-prevent-a-hamstring-injury/#:~:text=Since%20many%20hamstring%20injuries%20are,10%20minutes%20before%20more%20activity.

28. 5 Tips for Preventing Hamstring Injuries | Genesis Orthopaedic and ..., accessed February 17, 2025, https://gsamedicine.com/5-tips-for-preventing-hamstring-injuries/

29. Top 10 Tips for Preventing Hamstring Injuries | New York, NY, accessed February 17, 2025, https://www.orthopedicsurgeonnyc.com/blog/top-10-tips-for-preventing-hamstring-injuries/