Quick Facts About Hamstring Strains

hamstring strain

What are other terms for a hamstring injury?

  • Pulled hamstring
  • Hamstring strain
  • Torn hamstring
  • Ruptured hamstring

What is a hamstring strain?

Hamstring strains are one of the most common musculoskeletal injuries seen in active populations and make up 92% of muscular strains in soccer.1 Sports including track and field, soccer and weight lifting have been found to have high recurrence rates with respect to this injury. 2

The hamstring complex comprises three muscles in the back of your thigh. Starting from the inner part of your thigh and moving outwards, they are: semimembranosus, semitendinosus and biceps femoris. Any of these three muscles can become injured during activity. 

The hamstring muscles originate at the bottom of the pelvis and attach into the shin bones just below the knee. They are responsible for bending (flexion) at the knee and straightening (extending) the hip.3 When the hamstring complex is placed under a forceful load, this puts individuals at an increased risk for strains and ruptures. Studies indicate that a hamstring injury occurs most often during the late swing phase of sprinting, followed by eccentric loading (where the muscle is lengthening under load).3-4 

Muscular imbalances can also play a key role in hamstring injuries. For example the quadricep muscles are typically 20-30% stronger than the hamstring complex and imbalance between the two muscle groups can be problematic. Muscular weakness and improper firing patterns between the glutes and hamstring muscles are also very common amongst a wide range of people. Lastly, improper warm up prior to taking part in activities and sport puts one at a higher risk of sustaining a hamstring injury.3

How is the severity of a hamstring strain graded? 

Muscle strains can be separated into three categories based on the extent of damage to the tissues- Grades I, II, III.3

  • Grade I is considered a mild muscle strain with less than 10% of the fibers damaged. 
  • Grade II is a moderate muscle strain with approximately 11-99% of the fibers damaged.
  • Grade III is a severe muscle strain, also referred to as a full tear or rupture, with 100% of the fibers damaged. 

What are common signs and symptoms of a torn hamstring?

  • Decreased range of motion
  • Tender to touch
  • Pain with activity (running, sprinting, stretching)
  • Swelling and bruising
  • Decreased flexibility
  • Decreased strength
  • Muscular atrophy

What causes a torn hamstring? 

  • Explosive movements
  • High velocity sprinting
  • Accelerating too quickly 
  • Rapid change of direction 
  • Training errors
  • Overuse
  • Direct or indirect trauma
  • Returning back to play too soon
  • Improper warm-up
  • Muscular imbalances
  • Previous injuries

How is a hamstring injury diagnosed?

A registered physiotherapist or chiropractor can perform an assessment to aid in diagnosing a hamstring injury. This includes a detailed history of how the injury occurred, and a hands-on assessment to look at the muscle length, strength, and function. Typically, a referral for imaging, such as an ultrasound, is not necessary unless there is a suspected complete rupture. If this is the case, a consultation with a physician may be appropriate to be referred for imaging. 

What is the recovery time for a hamstring strain?

Muscle strains are one of the most common causes of time missed due to injury in a variety of sports.It is important to understand that recovery time will be different for every individual. Factors including mechanism of injury, degree of damage, age, training levels and past medical history can affect the length of recovery. Studies show that athletes sustaining a hamstring injury in elite sports such as rugby and football will most likely undergo a longer recovery period.7 Moreover, if you’re an athlete who participates in sports on a regular basis, your muscles are working even harder under forceful loads then the average person.

Tissue healing time is classified into three different phases: 9-10  

Inflammation – The inflammatory response phase typically occurs immediately following an injury and could last up to four days. Signs and symptoms of inflammation can include redness, associated pain, swelling, and warmth or heat to touch. The ultimate goal of the inflammatory phase is to prevent further blood loss at the lesion site. Moreover, this response causes blood vessels to constrict (vasoconstriction) which results in a blood clot or scab. 

Proliferation – Proliferation is the second phase of healing which begins around the fourth day post injury and could last up to twenty-one days depending on various factors. The key purpose of this phase is to clear the injury site of any debris. Cells will aid in developing new blood vessels and laying down connective tissue. 

Remodeling – The remodeling phase is the final phase of healing that begins approximately twenty-one days post injury and could last up to two years. The main purpose of this phase is for cells to overlap new tissue, joining the edges of the wound together. Collagen fibers are re-organized and scar tissue formation begins. 

How can therapy help for a pulled hamstring? 


  • Markerless motion capture to determine range of motion and identify areas of compensation
  • Gait or running analysis
  • Strength testing muscles of the lower extremity using a force dynamometer to establish a baseline and to identify any imbalances
  • A review of your current training program and any recent changes in footwear, frequency, surfaces etc. 


  • Specific stretching and strengthening exercises that will help increase flexibility and address strength deficits
  • A progressive loading program for the injured tissues so you can safely adapt back to the demands of your lifestyle and sport
  • Manual therapy to aid with swelling, pain and range of motion
  • Modifying activities and training program to fit your current stage of healing
  • Patient education and advice to help with pain management, prevent re-injury and body mechanics


  1. https://pubmed.ncbi.nlm.nih.gov/31937579/
  2. https://pubmed.ncbi.nlm.nih.gov/30426832/
  3. https://prohealthsys.com/wp-content/uploads/2016/08/5ExtremityManualPHSweb.pdf
  4. https://pubmed.ncbi.nlm.nih.gov/30356628/
  5. https://pubmed.ncbi.nlm.nih.gov/32561516/
  6. https://pubmed.ncbi.nlm.nih.gov/32024646/
  7. https://researchportal.bath.ac.uk/en/publications/can-we-modify-maximal-speed-running-posture-implications-for-perf
  8. https://bjsm.bmj.com/content/52/19/1275
  9. https://cdn.ps.emap.com/wp-content/uploads/sites/3/2015/11/111115_Wound-Management-1-Phases-of-the-wound-healing-process.pdf
  10. https://professionals.wrha.mb.ca/old/professionals/woundcare/documents/PrinciplesWoundHealing_WCCSpring2011.pdf

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