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Hamstring Injuries – Oh, The Agony!

Updated: Dec 5, 2023

Annually, hamstring injuries affect numerous individuals, particularly in sports requiring sudden accelerations—like athletics, football, or tennis. These injuries are known for slow healing and recurrence.

In this blog, we explore the diagnosis, treatment, and exercises for hamstring injuries, supplemented with demonstration videos for a comprehensive understanding.

The medical community is divided on the cause of these common injuries, with theories ranging from inadequate strength and muscle imbalances to poor warm-up routines. Generally agreed upon, these injuries mostly stem from internal factors, dubbed as 'Non-Contact Events.'

Article Index:


Examination & Diagnosis



Conclusion & References


Anatomy & Biomechanics

Hamstrings are no ordinary muscles. These bi-articular marvels stretch across not one but two vital joints, the hip and the knee. This dual connection renders them pivotal for our movements and paints a picture of how an injury can reverberate through your hips, lower back, knees, and the rhythm of your lower extremities.

Three distinct muscles form the hamstring's ensemble at the back of your thigh: the semitendinosus, semimembranosus, and biceps femoris. Together, they dance in unison, orchestrating your every step, jump, and run.

But what adds complexity to the hamstring's anatomy is the fascial connections, such as the posterior line. Imagine it as a web of interconnected threads, each pulling and influencing the others. A snag in one part of this web—such as a hamstring injury—can ripple across an extensive area, subtly altering the very symphony of your movement.

Semitendinosus Muscle: A Key Player in Movement

Originating from the lower pelvis (ischial tuberosity), the semitendinosus muscle weaves its way down to just below the inner knee (anterio-medial surface of the tibia) at a region known as the pes anserinus. Here, it joins with the gracilis and sartorius muscles—humorously abbreviated as GST, a nod to Canadian sales tax.

Sharing an attachment point with the long head of the biceps femoris, the semitendinosus plays a critical role in knee stability. When the bursa beneath these muscles inflames, it becomes a hotspot for knee pain.

Innervated by the tibial branch of the sciatic nerve (from spinal levels L5 to S2), it is more than just a muscle. The fascial expansion, including the semitendinosus, along with the sartorius, gracilis, semimembranosus, and gastrocnemius muscles, serves as intricate fascial tensors, stabilizing the medial side of the knee.

Semimembranosus Muscle

Originating from the same starting point as the semitendinosus in the lower pelvis (ischial tuberosity), the semimembranosus muscle journeys down the back of the leg to connect at the posterior medial tibia below the knee. This muscle is no stranger to injury, especially among dancers, where stretching mishaps are common.

Inflammation here can be deceptive, often mimicking an injury to the medial meniscus. The tibial division of the sciatic nerve gives life to this muscle, its roots tracing back to spinal levels L5 to S2.

What's more, the semimembranosus showcases a unique fascial feature, a small diagonal myofascial expansion that links with the crural fascia, enveloping the medial head of the gastrocnemius.

Meniscus Injuries

Easing restrictions in the semimembranosus can be a game-changer for meniscus function. The medial meniscus thrives on this fascial connection to the knee capsule, aiding in the retraction of the posterior horn. This complex interplay is a prime example of the delicate balance and finely tuned mechanics at work in our bodies.

Biceps Femoris Muscle: The Sprinter's Challenge

Frequently the site of hamstring injury, especially among sprinters, the biceps femoris stands out as an intricate component in the leg's mechanics. Comprising both a long and short head, this muscle plays a complex role.

The long head initiates its journey at the lower pelvis (ischial tuberosity), sharing its origin with the semitendinosus and the sacrotuberous ligament. Meanwhile, the short head sprouts from the outer side of the leg (posterolateral femur), and both unite just below the knee (head of the fibula and lateral condyle of the tibia).

Intriguingly, two distinct nerves breathe life into this muscle. The tibial division of the sciatic nerve energizes the long head, while the common fibular (peroneal) division ignites the short head. Both have roots ranging from spinal levels L4 to S2.

Fascial Expansion offers an impressive testament to the body's interconnectivity. Force effortlessly moves from the biceps femoris to the sacrotuberous ligament, reaching the erector spinae thoracolumbar fascia. With multiple myofascial expansions extending into the deep leg fascia (crural fascia), it becomes clear how low back pain may find its origins in the hamstring.

A noteworthy aside: The Adductor Magnus, often seen as another hamstring, can perplexingly manifest as medial hamstring pain when injured.


Functional Actions of the Hamstrings

The hamstring muscles serve multiple purposes: potent hip extensors (second only to the gluteus maximus muscle), knee flexors, medial and lateral rotators, and crucial knee stabilizers.

From a biomechanical standpoint, depending on leg position, the hamstrings can perform various actions:

  • All hamstring muscles extend the thigh at the hip joint, flex the leg at the knee, and tilt the pelvis in a posterior direction.

  • The semimembranosus and semitendinosus medially rotate the leg inward.

  • The biceps femoris laterally rotates the leg outward. Note: The short head of the biceps femoris does not directly participate in hip movement, as it does not cross the hip joint.

Some researchers have emphasized specific hamstring actions while considering other actions as secondary or less important functions. For instance, some studies have demonstrated that the hamstrings can act as knee flexors, but only in nonfunctional settings. As a result, only the so-called primary tasks (such as hamstring extension) are considered in standard training or rehabilitation routines.

Personally, I regard the hamstrings as a multifunctional, intricate structure filled with neurological receptors that communicate information to other muscles, enabling them to execute numerous additional tasks.


Running Related

While running, your hamstrings serve as shock absorbers, force generators, and stabilizers.

Shock absorption occurs through the eccentric contraction of the hamstring muscles, which effectively absorbs the kinetic energy from foot impact. This shock absorption mechanism works best when the hamstrings remain strong, flexible, and free from adhesion or fibrosis resulting from previous injuries.

The hamstrings also play a crucial role in force generation, as they work synergistically with the gluteal muscles during hip extension.

The hamstrings provide stabilization while running in several ways:

  • They function as dynamic stabilizers by slowing down the forward movement of the shin bone (tibia) during knee extension, which is similar to the action of the anterior cruciate ligament (ACL). However, the ACL serves as a passive stabilizer.

  • After the initial ground contact, the hamstrings lengthen to stabilize the knee.

  • During the push-off phase with the foot, the hamstrings contract (together with the quadriceps) to provide propulsion.


Hamstring Tears

Following an initial tear of the hamstring muscle, there is typically some bleeding, which may appear as a small to large bruise over the hamstrings.

The bleeding from a hamstring tear is succeeded by an inflammatory response, leading to an increase in fibroblast cells. Fibroblasts play a role in collagen synthesis (which provides the structural framework for all tissues), wound healing, and scar tissue formation.

As the inflammatory response of a hamstring injury begins to subside, scar tissue (fibrosis) can develop. Scar tissue is weak, inflexible, and prone to re-injury, and it can decrease the range of motion and generate abnormal movement patterns. This fibrotic tissue and the resulting imbalances contribute to the high rate of re-occurrence of hamstring injuries.

From a pain perspective, most hamstring injuries seem to heal over time. In reality, these injuries often do not fully recover but become the starting point for a series of other injuries caused by the residual tissue alteration and the resulting biomechanical compensations that this tissue creates.

Grading a Hamstring Injury

Assessing the severity of a hamstring injury is crucial to determine appropriate treatments. Hamstring strains are graded from 1 to 3, with 3 being the most severe.

Hamstring - Grade 1 Strain:

  • The affected person can still walk, albeit with some difficulty.

  • There may be minor swelling, stiffness, and pain.

  • In a Grade 1 Strain, only minor tearing of the hamstring muscle occurs. Comparing a muscle to a piece of tissue paper, there are only minor tears in a Grade 1 injury.

  • There should be only minor pain during hamstring resistance testing, with no significant loss of strength.

Hamstring - Grade 2 Strain:

  • The injured person may have difficulty walking and could experience considerable pain.

  • There may be swelling with some degree of bruising.

  • In a Grade 2 Strain, moderate tearing of the muscle occurs. Using the tissue paper analogy, there would be a significant number of tears compared to a Grade 1 Sprain.

  • The patient may not be able to straighten their knee, with considerable pain during hamstring resistance testing.

Hamstring - Grade 3 Strain:

  • A Grade 3 Strain involves severe or complete tearing of the muscle. Using the tissue paper analogy, the tissue could be torn into two pieces. This type of strain might require surgical intervention to reattach the muscle.

  • Any action that causes the hamstrings to contract will result in severe pain.

  • Walking will be extremely difficult; the injured person will need crutches, and there could be a complete loss of function.



A comprehensive diagnostic evaluation for hamstring injuries necessitates a multi-faceted approach that blends a detailed patient history with focused orthopedic tests. Here's are examples of orthopedic, neurological, and vascular examinations that we commonly perform on our patients. To rule out other problems we often apply tests from both the knee and hip examinations.

Orthopedic Testing:

Knee Examination: This video provides an in-depth look at orthopedic testing techniques tailored for knee examination. These tests are crucial for diagnosing multiple conditions.

Hip Examination - Orthopaedic Testing - In this video, we will be discussing the various orthopedic tests used for examining the hip joint to diagnose and treat hip-related conditions.

Neurological Testing:

Lower Limb Neuro Examination - The lower limb neurological examination assesses the motor and sensory neurons supplying the lower limbs to detect any nervous system impairment. This examination is used both as a screening and investigative tool.

Vascular Testing

Peripheral Vascular Examination - The peripheral vascular examination is a physical exam that evaluates the circulatory system outside of the heart and lungs. This exam is important in diagnosing and managing peripheral vascular diseases such as arterial occlusion, aneurysms, and venous insufficiency.

Specialized Orthopedic Tests for Patellar Tendinopathy:

  • Single-Leg Decline Squat: Instruct the patient to stand on a declined surface (10-25 degrees) with one leg. Ask them to perform a single-leg squat while observing for pain or instability. Pain during this test can indicate patellar tendinopathy.

  • Resisted Isometric Knee Extension: With the patient seated and knee flexed to 90 degrees, apply a resistive force against their lower leg as they try to extend their knee. Pain or weakness may indicate a compromised patellar tendon.

  • Functional Limitations Assessment: Evaluate the patient’s ability to complete tasks that load the patellar tendon, like squatting or jumping. Note any limitations in range of motion, strength, or performance.


In hamstring injury cases, X-rays rule out fractures and identify potential pathological processes. However, X-rays do not provide information about the actual tear itself.

The most effective imaging modality for visualizing a hamstring injury is Magnetic Resonance Imaging (MRI). Although Computed Tomography (CT) scans and ultrasound can also be useful, they are not as definitive as an MRI. The advantage of ultrasound lies in its lower cost.

In summary, when assessing hamstring injuries, various imaging techniques can be used:

  1. X-rays: Useful for ruling out fractures and identifying potential pathological processes, but do not reveal information about the tear.

  2. MRI: Offers the most detailed visualization of hamstring injuries, allowing for accurate assessment of the extent of the damage.

  3. CT scans: While they can provide some insight into the injury, they are not as definitive as MRI.

  4. Ultrasound: A lower-cost option that can still offer valuable information about the injury, but may not be as detailed as MRI.


Motion Specific Release

Prompt mobilization with manual therapy of the injured hamstring is crucial for a swift recovery. This can involve passive stretching and strengthening exercises within a pain-free range of motion.

Initially, isometric strengthening exercises are suggested, followed by a gradual progression to isotonic exercises. Isometric exercises involve static muscle contractions without noticeable joint angle movement. In contrast, isotonic exercises maintain constant tension while the muscle's length changes, as in weightlifting.

In the following videos, Dr. Abelson, the developer of Motion Specific Release (MSR) demonstrates some of the treatment procedures that are commonly used in treating hamstring injuries. Which procedures are used will depend on the specific case.

Effective Hamstring Release Procedures

In this video Dr. Abelson demonstrates effective hamstring release procedures. A hamstring restriction (or Injury grade 1 or 2) responds well to a combination of manual therapy and exercise.

MSR Gluteus Maximus Protocol

Dr. Abelson, the Motion Specific Release (MSR) developer, demonstrates specific procedures to release restrictions in the gluteus maximus muscle to alleviate pain caused by muscle tightness from prolonged sitting, overuse, or excessive athletic performance. These procedures aim to restore normal muscle function, improve mobility and alleviate symptoms caused by tightness and restrictions. Strong, flexible, engaged gluteal muscles are critical to optimum performance and injury prevention.


Treatment Frequency

The frequency of manual treatment is tailored to the severity of the injury. Mild injuries often require less intensive therapy, allowing for an early transition to self-managed care. Moderate injuries demand a more structured approach to navigate through healing phases and initiate rehabilitation. Post-surgical rehabilitation necessitate intensive, prolonged therapy to ensure optimal recovery, manage scar tissue, and restore function while preventing secondary complications. Each injury grade thus dictates a distinct therapy approach and frequency, aligning with individualized therapeutic needs for optimal healing and functionality restoration.

Grade 1 Tear (Mild):

  • Initial: 2 times per week

  • Duration: 1-2 weeks, transitioning to home exercises and self-management

  • Approximate Total Appointments: A total of 3 to 6 appointments, followed by 1 or 2 follow-up appointments, depending on patient response.

Grade 2 Tear (Moderate):

  • Initial: Weekly to bi-weekly visits

  • Duration: 2-4 weeks, then tapering off as symptoms improve and home exercises progress

  • Approximate Total Appointments: 3 to 8 appointments, comprising weekly to bi-weekly visits over a span of 2-4 weeks, followed by 1 or 2 follow-up appointments, depending on patient response.

Grade 3 Tear (Severe - Requires Surgery):

When surgery is required, post-operative rehabilitation begins with managing pain and swelling and immobilizing the ankle. Early rehabilitation introduces weight-bearing and basic exercises. Intermediate rehabilitation advances strengthening and normalizes walking. Late rehabilitation intensifies strength training and introduces sport-specific exercises. Finally, a gradual return to full activities, usually within 4 to 6 months.



It is crucial to train the hamstrings in a manner that reflects their function in real-life activities. The hamstrings work synergistically with multiple muscles and do not act as isolated muscles. For instance, hamstrings should be trained in both open and closed kinetic chain movements to simulate hamstring muscle function during running. Closed-chain exercises can replicate the Stance Phase of running, while open-chain exercises can simulate the Swing Phase of running (eccentric actions).

The following presents a typical exercise protocol that may be used to address hamstring injuries. Of course, this would be customized to meet each patient's specific needs and injury status. The load placed on the hamstrings must be appropriate for the individual.

The First Two to Three Weeks After the Injury

  • Minimize atrophy and loss of strength.

  • Prevent motion loss.

  • Protect healing tissue.

  • Avoid abnormal gait pattern development.

  • Avoid excessive active or passive lengthening of hamstring.

Rehabilitation Exercises
  • Ice – 2-3 times daily.

  • Stationary bike.

  • Isometric exercises.

  • Progressive hip strengthening.

  • Sciatic nerve flossing exercises.

  • Single leg balance exercises.

When to progress to the next phase
  • Normal gait patterns are regained without pain

  • The patient can perform pain-free isometric contraction (50%-75%) during prone knee flexion at 90 degrees. (9)

Weeks Three to Twelve After Injury

  • Develop neuromuscular control to start developing functional movement patterns.

  • Regain hamstring range of motion and strength (pain-free).

  • Avoid painful ROM, especially at end range.

Rehabilitation Exercises
  • Stationary bike (20 to 30 minutes).

  • Treadmill, pain-free speed and stride (moderate intensity).

  • Eccentrics hamstring loading exercises.

  • Sciatic nerve flossing and tensioning exercises.

  • Single leg stance on wobble board exercises.

  • Supine hamstring curls on Swiss ball exercises.

  • Walking band exercises.

  • Tantrums

Criteria for progression to the next phase
  • Resumption of full strength.

  • Pain-free forward and backward gait (moderate intensity).

  • Strength at 80% of uninjured leg.

Week Twelve Plus After Injury

  • Improve neuromuscular control.

  • Normal concentric and eccentric strength through full AROM.

  • Pain and symptom-free during all activities.

  • All exercises must be within a pain-free range of motion.

Rehabilitation Exercises
  • Treadmill moderate to high intensity as tolerated.

  • Dead-lift exercises.

  • Squat jump, single leg jump, lateral hop exercises.

  • Box jump exercises.

  • Eccentric lunge drop exercises.

  • Forward and backward skipping exercises.

Return to Sport Criteria
  • Full strength without pain with normal AROM.

  • Bilateral symmetry in knee flexion under load.

  • Full AROM (no pain).

  • Duplication of sport-specific movements without symptoms.



The journey through hamstring injuries underscores the imperative of an informed, nuanced, and individualized approach toward diagnosis, treatment, and rehabilitation. The anatomy and biomechanics of the hamstring muscles provide a canvas for understanding their functional roles, especially in activities like running. The meticulous delineation of hamstring tears, coupled with comprehensive orthopedic examinations, fosters an evidence-based and holistic approach toward effective recovery.

Dr. Abelson's Motion Specific Release Procedures unveil a structured path for swift recovery tailored to the injury's severity. These procedures, alongside the staged rehabilitation exercises, underscore the essence of personalized therapeutic interventions. The outlined functional hamstring exercises further spotlight the importance of training these muscles in a manner resonating with their real-life functional roles, thereby fostering a well-rounded rehabilitation process. The phased approach, from immediate post-injury care to the eventual return to sport, emphasizes a tailored, progressive, and cautious strategy aiming for a full recovery and safe sporting environment.



Dr. Abelson's approach in musculoskeletal health care reflects a deep commitment to evidence-based practices and continuous learning. In his work at Kinetic Health in Calgary, Alberta, he focuses on integrating the latest research with a compassionate understanding of each patient's unique needs. As the developer of the Motion Specific Release (MSR) Treatment Systems, he views his role as both a practitioner and an educator, dedicated to sharing knowledge and techniques that can benefit the wider healthcare community. His ongoing efforts in teaching and practice aim to contribute positively to the field of musculoskeletal health, with a constant emphasis on patient-centered care and the collective advancement of treatment methods.


Revolutionize Your Practice with Motion Specific Release (MSR)!

MSR, a cutting-edge treatment system, uniquely fuses varied therapeutic perspectives to resolve musculoskeletal conditions effectively.

Attend our courses to equip yourself with innovative soft-tissue and osseous techniques that seamlessly integrate into your clinical practice and empower your patients by relieving their pain and restoring function. Our curriculum marries medical science with creative therapeutic approaches and provides a comprehensive understanding of musculoskeletal diagnosis and treatment methods.

Our system offers a blend of orthopedic and neurological assessments, myofascial interventions, osseous manipulations, acupressure techniques, kinetic chain explorations, and functional exercise plans.

With MSR, your practice will flourish, achieve remarkable clinical outcomes, and see patient referrals skyrocket. Step into the future of treatment with MSR courses and membership!



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