What it is

Strains are overstretch or tearing of muscle fibres. In the hip and groin region, hamstrings, adductors, hip flexors, and quadriceps are common sites.

People feel a sudden pull or sharp pain with sprinting, kicking, or stretching under load. Swelling and bruising follow with higher-grade tears.

What happens when it occurs

Excessive tensile load or explosive contraction disrupts fibres. Early graded loading promotes organised healing and reduces scar adhesions.

Common causes and risk factors

  • High-speed running and kicking
  • Previous strain, poor strength balance, or fatigue
  • Rapid increases in training volume or intensity

Who is most affected

Field and court athletes, sprinters, and recreational runners.

Typical symptoms

  • Sudden pain at the time of injury
  • Pain on stretch and contraction
  • Bruising and weakness in higher grades

When to seek care

If walking is difficult, if bruising is extensive, or if strength does not improve over the first week.

How we diagnose

History and examination, strength and length testing. Ultrasound or MRI defines extent when needed for grading or return-to-play planning.

Management

  • Early protected range and isometrics, then heavy slow resistance
  • Eccentric-biased work and sprint or change-of-direction progressions
  • Address strength balance and technique

Rehabilitation milestones

Phase 1 days 0 to 5: pain control, isometrics at short lengths, gentle range.

Phase 2 days 5 to 21: heavy slow loading, progressive lengthening work.

Phase 3 weeks 3 to 6: acceleration, deceleration, cutting, kicking drills.

Phase 4 weeks 6 to 12: return to play integration with sprint or power targets.

Readiness to progress

  • No pain on palpation or stretch
  • Strength testing within 90 percent and symmetric length tolerance
  • Sprint or kicking test completed without pain

Prevention

  • Eccentric strength for hamstrings and adductors
  • Sprint exposure and change-of-direction drills in training
  • Manage fatigue and progress volumes gradually

Australia snapshot

  • Hamstring strain is a leading time-loss injury in football codes
  • Adductor and hip flexor strains feature in kicking sports
  • Recurrence risk is highest in the first weeks after return if criteria are not met

Latest insights

Eccentric loading and sprint exposure reduce recurrence better than rest.

Return to play is safest with criteria that include strength, length tolerance, and sprint or kicking tests.

Frequently Asked Questions

Grade I strains often take 2 to 3 weeks, grade II 4 to 8 weeks, and grade III longer depending on the site and management.

Keep easy running or bike if it is pain-free during and the next day. Avoid sprinting and kicking until strength and length tolerance improve.

Imaging helps when the diagnosis is uncertain, when a higher-grade tear is suspected, or when milestones stall.

Heavy slow resistance progressing to eccentric work at longer muscle lengths, plus sprint or change-of-direction exposure.

Meet return criteria, keep eccentric strength, and maintain sprint or kicking exposure in training.

Usually possible with task changes. Avoid sudden lunges or heavy lifting until strength returns.

When palpation and stretch are pain-free, strength is within 90 percent, and you pass your sprint, hop, or kicking tests.