Semitendinosus Trigger Points

Introduction

The semitendinosus is a major hamstring muscle responsible for knee flexion, hip extension, and lower limb stability. When trigger points develop in this muscle, they can cause posterior thigh pain, knee stiffness, and limited hip mobility, often mimicking hamstring strain, sciatica, or knee joint dysfunction.

Name and Area

  • Name: Semitendinosus

  • Area: Located in the posterior thigh, running from the ischial tuberosity (sit bone) to the medial tibia (pes anserinus area).

Indications

Semitendinosus trigger points may contribute to:

  • Pain in the back of the thigh (mistaken for hamstring strain or sciatic nerve irritation)

  • Pain or tightness that extends to the inner knee and upper calf (can mimic medial knee dysfunction or nerve pain)

  • Stiffness in the hamstrings that restricts knee flexion and hip extension

  • Pain when running, walking, or sprinting (common in athletes, runners, and cyclists)

  • Weakness in knee flexion (difficulty bending the knee or performing deep squats)

  • Pain that worsens with sitting for long periods or after intense physical activity

Pain from this muscle is often mistaken for hamstring tendinopathy, sciatic nerve irritation, or pes anserinus bursitis.

Muscle Action

  • Flexes the Knee: Bends the leg backward, essential for walking, running, and jumping.

  • Extends the Hip: Helps move the thigh backward, important for gait and sprinting mechanics.

  • Medially Rotates the Lower Leg: Assists in stabilizing the knee joint during movement.

The semitendinosus is crucial for lower body strength, knee stability, and hip mobility.

Signs and Symptoms

Individuals with semitendinosus trigger points often report:

  • Pain in the posterior thigh that feels like a dull, aching sensation

  • Pain that extends to the inner knee and upper calf (can resemble medial knee or nerve pain)

  • Restricted hamstring flexibility, making it difficult to fully extend the leg

  • Pain that increases with sprinting, deep squats, or explosive leg movements

  • Weakness or instability when bending the knee or extending the hip

  • Pain that worsens after prolonged sitting or standing

Pain worsens with excessive knee flexion, prolonged sitting, or sudden sprinting movements.

Perpetuating Factors

Common causes of semitendinosus trigger points include:

  • Overuse in running, sprinting, or jumping sports (common in soccer, basketball, and track athletes)

  • Prolonged sitting with knees bent (can lead to chronic tightness and restricted mobility)

  • Weak or imbalanced hip and gluteal muscles (forces the hamstrings to compensate for stability)

  • Poor sprinting mechanics or sudden acceleration (can cause microtears and trigger point formation)

  • Inadequate hamstring stretching or recovery after intense exercise

Trigger Point Referral Pattern

Trigger points in the semitendinosus refer pain to:

  • The posterior thigh and knee (can mimic hamstring strain or sciatic pain)

  • The medial knee and upper calf (mistaken for knee ligament or meniscus dysfunction)

  • The inner thigh and groin (can resemble adductor strain or hip dysfunction)

Pain from this muscle is often confused with hamstring tendinopathy, sciatic nerve irritation, or knee instability.

Differential Diagnosis

Semitendinosus trigger points may be mistaken for:

  • Hamstring strain (pain in the posterior thigh, common in runners and athletes with sudden leg movements)

  • Sciatica (pain radiating down the back of the leg, often due to nerve compression in the lower back)

  • Medial meniscus tear (inner knee pain, worsens with twisting or squatting movements)

  • Pes anserinus bursitis (pain on the medial knee, common in runners and cyclists)

  • Gluteal dysfunction (weakness or imbalances in the hips that affect leg mechanics and knee stability)

A thorough hip, knee, and lower limb examination is necessary to rule out these conditions.

Associated Trigger Points

Semitendinosus trigger points often co-exist with:

  • Biceps femoris (lateral hamstring and knee pain, affects sprinting and jumping mechanics)

  • Adductor magnus (inner thigh and groin pain, can contribute to hip and pelvic imbalances)

  • Gluteus maximus (buttock and posterior thigh pain, affects hip extension and lower limb power)

  • Quadratus femoris (deep hip pain, affects external rotation and hip stability)

Anatomy and Innervation

Muscle Origin Insertion Innervation
Semitendinosus Ischial tuberosity (sit bone) Medial tibia (pes anserinus area) Tibial branch of the sciatic nerve (L5–S2)

The semitendinosus is innervated by the tibial branch of the sciatic nerve, which also controls knee flexion, hip movement, and lower limb coordination.

Patient Examination

A comprehensive examination should include:

  • Palpation: Identify tender nodules along the posterior thigh and medial knee.

  • Resisted Knee Flexion Testing: Assess pain and weakness when bending the knee against resistance.

  • Gait and Postural Analysis: Look for hip instability, excessive knee valgus, or altered stride mechanics.

  • Hamstring Flexibility and Strength Testing: Rule out muscle imbalances, tightness, or previous hamstring injuries.

Corrective Actions

Dry Needling

  • Dry needling can release trigger points in the semitendinosus, reducing thigh tightness and improving knee function.

Manual Therapy

  • Trigger Point Release: Apply deep sustained pressure to tight spots in the posterior thigh and medial knee.

  • Massage Therapy: Helps improve circulation and reduce hamstring muscle tension.

Stretching

  • Seated Hamstring Stretch: Helps lengthen the semitendinosus and improve flexibility.

  • Lunge Stretch with Knee Extension: Helps reduce tension in the posterior thigh and knee.

Strengthening Exercises

  • Nordic Hamstring Curls: Strengthens the hamstrings for better knee stability and injury prevention.

  • Single-Leg Romanian Deadlifts: Improves posterior chain activation and hip stability.

  • Glute Bridges: Helps counteract hamstring tightness and engage the posterior chain.

Postural and Movement Adjustments

  • Avoid overloading the hamstrings without proper warm-up (ensure dynamic stretching before running or sprinting).

  • Improve running mechanics (engage the core and avoid overstriding to reduce hamstring overuse).

  • Incorporate dynamic hip mobility drills (prevents excessive tightness and improves functional movement).

Conclusion

The semitendinosus plays a crucial role in knee flexion, hip stability, and lower body power, but trigger points in this muscle can cause significant posterior thigh, knee, and calf pain. By incorporating dry needling, manual therapy, stretching, and strengthening exercises, individuals can reduce pain, improve mobility, and prevent chronic hamstring dysfunction.

➡️ Learn more about Trigger Points

➡️ Explore our Trigger Point Index

Sources:

  • Travell, J. G., & Simons, D. G. (1983). Myofascial Pain and Dysfunction: The Trigger Point Manual (2nd ed.). Williams & Wilkins.

  • Simons, D., & Travell, J. (1999). The Trigger Point Manual, Volume 2: The Lower Extremities. Williams & Wilkins.