Hamstring Injuries

The hamstrings are a group of three muscles located at the back of the thigh that work together to bend the knee and extend the hip. They play a key role in walking, running, sprinting and sudden acceleration or deceleration movements.

Hamstring injuries occur when these muscles or their tendons are overstretched or overloaded, leading to tissue damage that affects function and movement. These injuries are common in both athletes and active individuals and can significantly limit mobility and performance if not assessed and managed appropriately.

What are the types of hamstring injuries?

The injuries can be classified based on the nature and location of tissue damage:

• Hamstring strain — stretching or tearing of muscle fibres, typically occurring during sprinting or sudden acceleration.
• Partial hamstring tear — more significant fibre disruption with pain, weakness and functional limitation.
• Complete hamstring rupture — full-thickness tear of the muscle or tendon, sometimes with tendon retraction.
• Proximal hamstring tendinopathy — chronic degeneration or irritation of the hamstring tendon near its attachment at the pelvis.
• Avulsion injury — the hamstring tendon pulls away from the bone, occasionally taking a small bone fragment with it.

What causes hamstring injuries?

Hamstring injuries can result from a variety of causes, such as:

• Sudden acceleration or sprinting — high-speed running places strong eccentric forces on the hamstrings.
• Rapid changes in direction or deceleration — common in court and field sports.
• Muscle fatigue — tired muscles are less able to absorb load and are more prone to injury.
• Insufficient warm-up — reduced muscle readiness increases strain during explosive movements.
• Strength imbalance — relatively weaker hamstrings compared to quadriceps increases injury risk.
• Reduced flexibility — tight hamstrings are less tolerant to sudden stretch.
• Previous hamstring injury — scar tissue and altered mechanics increase susceptibility to reinjury.

What are the symptoms of hamstring injuries?

Some of the common symptoms include:

• Sudden sharp pain in the back of the thigh
• A pulling or tearing sensation during activity
• Localised tenderness or pain on palpation
• Swelling or bruising in the posterior thigh
• Weakness when bending the knee or extending the hip
• Difficulty walking, running or climbing stairs

Who is at risk of hamstring injuries?

Certain populations are more vulnerable to hamstring injuries because of how their activities, physical characteristics or training demands place increased stress on the posterior thigh muscles:

• Older adults — age-related reductions in muscle elasticity, strength and healing capacity increase vulnerability to muscle and tendon injuries.
• Individuals with a history of hamstring injury — previous injury can leave residual weakness, scar tissue or altered neuromuscular control, reducing the muscle’s ability to tolerate future strain.
• Athletes involved in sprinting or explosive sports — sports such as football, rugby and athletics require rapid acceleration and deceleration, exposing the hamstrings to repeated high-load eccentric contractions.
• People with strength imbalances between muscle groups — disproportionately strong quadriceps relative to hamstrings increases eccentric loading on the hamstrings during high-speed knee extension.
• Individuals with limited hamstring flexibility — reduced ability of the muscle to lengthen under load increases susceptibility to strain during sudden movements.
• Those undergoing high training volumes or inadequate recovery — insufficient recovery time limits tissue repair and adaptation, increasing fatigue-related injury risk.
• Individuals returning to sport too quickly after injury — incomplete rehabilitation may result in residual weakness or poor movement control, increasing the likelihood of reinjury.

How are hamstring injuries diagnosed in Singapore?

Dr James Tan performs a structured evaluation to confirm the diagnosis, assess severity and rule out other causes of posterior thigh pain.

• Clinical history  — a detailed history helps identify the mechanism of injury, including:
  • Sudden onset during sprinting or activity
  • Gradual pain associated with overuse
  • Previous hamstring injuries or recurrence
  • Functional limitations following injury
• Symptom review — the symptom patterns provide insight into injury severity:
  • Location and intensity of pain
  • Presence of swelling or bruising
  • Functional limitations in walking or running
  • Progression or improvement with rest
• Physical examination — the examination typically includes:
  • Palpation to identify tenderness or defects
  • Assessment of range of motion and flexibility
  • Strength testing of knee flexion and hip extension
  • Functional movement assessment
• Imaging examination — imaging may be arranged to assess the extent of muscle or tendon injury:
  • Ultrasound — to assess muscle fibre disruption or haematoma
  • Magnetic Resonance Imaging (MRI) — to define injury extent, tendon involvement or avulsion injuries when symptoms are severe or persistent

How are hamstring injuries graded?

The condition is graded based on severity. This includes:

• Grade 1 (Mild) — minimal muscle fibre damage with mild pain and little strength loss.
• Grade 2 (Moderate) — partial tear with pain, swelling and noticeable weakness.
• Grade 3 (Severe) — complete tear or rupture with significant loss of function.

How are hamstring injuries treated in Singapore?

Once a diagnosis has been confirmed, our doctor will outline a treatment plan, which may involve.

Conservative management

• Activity modification — avoiding movements that aggravate symptoms during early healing.
• Load management — gradual reintroduction of activity based on symptom tolerance.
• Pain management — ice application and prescribed analgesics when appropriate.
• Education — guidance on safe movement and recovery expectations.

Non-surgical interventions

• Physiotherapy programmes — structured strengthening, flexibility and neuromuscular control exercises.
• Shockwave Therapy (ESWT) — may be used in selected cases of chronic proximal hamstring tendinopathy.
• Platelet-Rich Plasma (PRP) injections — occasionally considered in persistent tendinopathy or partial tears where healing is delayed.
• Supportive bracing or taping — temporary support during rehabilitation.

Surgical management (selected cases)

• Fracture fixation or tendon reattachment — considered for avulsion injuries or complete tendon ruptures.
• Surgical repair or tendon reattachment — used selectively when conservative treatment fails or significant structural damage is present.

Rehabilitation and return to activity

• Progressive strengthening — restoring hamstring strength and endurance.
• Flexibility training — gradual lengthening to restore normal muscle function.
• Movement retraining — correcting running or sport-specific mechanics.
• Graduated return-to-sport planning — based on functional milestones rather than fixed timelines.
• Recurrence prevention strategies — addressing contributing risk factors.

Book an Appointment

Hamstring injuries are often underestimated, but inadequate recovery increases the risk of recurrence and prolonged downtime. Early assessment helps determine injury severity and guides appropriate management.
If you experience sudden posterior thigh pain, ongoing weakness or repeated hamstring issues, booking an appointment with Dr James Tan allows for a personalised treatment plan focused on recovery, performance and long-term muscle health.