Sudden pain in the back of your thigh while sprinting. You may have suffered a hamstring strain, one of the most common muscle injuries among athletes. This injury accounts for 37% of muscle injuries in professional soccer and affects both amateur and professional athletes.

Good news: with the right treatment and proper rehabilitation, the vast majority of muscle strains heal completely. Here's what you need to know to recover properly.

What is a hamstring strain?

A hamstring strain is a tear in the muscle fibers at the back of the thigh, affecting one or more of the three muscles that make up this group: the biceps femoris, semitendinosus, and semimembranosus.

The hamstrings are composed of three distinct muscles. The biceps femoris is located on the outer side of the thigh, while the semitendinosus and semimembranosus occupy the inner side.

The biceps femoris is the most commonly affected muscle, accounting for 53% of hamstring injuries. These injuries typically occur at the myotendinous junction, where the muscle meets the tendon.

| Type | Muscle affected | Mechanism | Typical example |

|------|---------------|-----------|-----------------|

| Type 1 (sprint) | Biceps femoris | Explosive contraction | Sprinting, acceleration |

| Type 2 (stretching) | Semi-membranous | Excessive stretching | Splits, high kick |

The hamstrings play an essential role: they flex the knee, extend the hip, and stabilize the pelvis during running.

What causes hamstring strains?

A muscle strain occurs during a powerful eccentric contraction, typically during the acceleration phase of a sprint, when the muscle lengthens while contracting to slow down the movement of the leg.

The critical moment occurs just before the foot touches the ground during a sprint, during the terminal swing phase. Contrary to what one might think, the risk is not highest at maximum speed, but during maximum acceleration.

A meta-analysis published in the British Journal of Sports Medicine identifies the following risk factors:

| Risk factor | Relative risk | Impact |

|-------------------|----------------|--------|

| History of hamstring injury | 2.7 to 6 times higher | Most significant factor |

| Age over 25 | 1.3 to 1.9 times higher | Progressive risk |

| Low eccentric force | Significant | Measurable by tests |

| Bilateral imbalance >10-15% | Significant | Correctable |

Fatigue at the end of the game significantly increases the risk. That is why injuries are more common in the second half.

| Sport | Prevalence | Typical mechanism |

|-------|------------|-------------------|

| Sprint athletics | 16-26% of injuries | Acceleration |

| Soccer | 12-16% of injuries | Sprinting, shooting |

| American football | 12% of injuries | Sprinting, tackling |

| Dance and ballet | 8-17% of injuries | Splits, extension |

Who is at risk of hamstring strain?

Athletes who have already suffered a hamstring strain are at the highest risk of re-injury, with a recurrence rate of 12 to 33% depending on the study.

The incidence in professional soccer is 0.87 to 1.8 injuries per 1,000 hours of play. Players who have already suffered a strain are particularly vulnerable.

| Factor | Risk threshold | Measure |

|---------|-----------------|--------|

| History of muscle strain | Any previous injuries | History |

| Age | Over 25 | Non-modifiable factor |

| H:Q ratio | Less than 0.6 | Strength test |

| Unilateral deficit | More than 10% | Bilateral comparison |

| Knee flexibility | Reduced | Mobility test |

Recurrence is often more severe than the initial injury. That is why complete rehabilitation before returning to sport is essential.

How can you recognize the symptoms of a hamstring strain?

The main symptom is sudden, localized pain in the back of the thigh, often accompanied by a popping sensation. Approximately 70% of athletes report this "pop" sensation at the moment of injury.

| Symptom | Mild | Moderate | Severe |

|----------|-------------|--------------|--------------|

| Pain | Mild, localized | Moderate, diffuse | Intense, debilitating |

| Walking | Possible with discomfort | Difficult | Impossible |

| Bruising | Absent or slight | Visible for 48-72 hours | Extensive |

| Swelling | Minimal | Moderate | Significant |

• Palpation: specific tender point at the back of the thigh
• Active knee extension test: painful limitation
• Passive stretch test: pain when stretching the muscle
• Isometric strength test: weakness and pain

• Complete inability to put weight on the leg
• Extensive bruising extending down to the knee
• Palpable depression in the muscle (suggests a rupture)
• Severe pain that persists even at rest

What are the different degrees of severity?

Hamstring strains are classified into four grades according to the extent of tissue damage, ranging from simple pain with no visible injury to complete muscle rupture.

The British Athletics Muscle Injury classification distinguishes between the following grades:

| Grade | Description | Affected fibers | Return to sport timeframe |

|-------|-------------|-----------------|-------------------|

| Grade 0 | Pain without structural damage | 0% | Less than one week |

| Grade 1 | Small intra-fascicular lesion | Less than 10% | 1 to 3 weeks |

| Grade 2 | Moderate interfascial lesion | 10 to 50% | 4 to 8 weeks |

| Grade 3 | Extensive injury or rupture | More than 50% | 3 to 6 months |

| Method | Sensitivity | Indication |

|---------|-------------|------------|

| Ultrasound | 68-92% for grades 2-3 | Initial examination, rapid |

| MRI | Reference for all grades | Precise localization, prognosis |

Two factors worsen the prognosis: a proximal location (close to the buttock) and tendon involvement rather than muscle involvement.

How to treat a hamstring strain?

Treatment is based on the PEACE and LOVE protocol, a modern approach that replaces the old RICE protocol and promotes optimal tissue healing.

| Letter | Principle | Practical application |

|--------|----------|---------------------|

| P | Protection | Avoid activities that cause pain |

| E | Elevation | Raise the leg to promote drainage |

| A | Avoid anti-inflammatory drugs | Avoid NSAIDs, which can interfere with healing |

| C | Compression | Bandage to reduce swelling |

| E | Education | Understanding that optimal load promotes healing |

| Letter | Principle | Practical application |

|--------|----------|---------------------|

| L | Load | Gradually introduce mechanical stresses |

| O | Optimism | A positive attitude improves the prognosis |

| V | Vascularization | Pain-free cardiovascular activity |

| E | Exercise | Restore mobility, strength, and proprioception |

| Phase | Type of exercise | Objective |

|-------|-----------------|----------|

| 1 | Isometric | Muscle activation without movement |

| 2 | Concentric | Strengthening through shortening |

| 3 | Eccentric | Strengthening through stretching |

| 4 | Sport-specific | Preparation for return |

The Nordic hamstring exercise reduces the risk of injury by 51% and speeds up recovery. Askling's L protocol allows for a faster return to sport than conventional approaches.

• Strength greater than 90% compared to the healthy side
• Absence of pain on palpation
• Successful completion of functional tests (jumps, accelerations, decelerations)
• Regained psychological confidence

How long does healing take?

The healing time varies from 2 weeks for a grade 1 tear to 6 months for a complete tear, with a gradual return based on objective criteria rather than a fixed schedule.

| Grade | Protected phase | Active rehabilitation | Return to sport |

|-------|----------------|---------------------|-----------------|

| Grade 1 | 3 to 5 days | 1 to 2 weeks | 2 to 3 weeks |

| Grade 2 | 1 to 2 weeks | 3 to 5 weeks | 4 to 8 weeks |

| Grade 3 | 4 to 6 weeks | 6 to 12 weeks | 3 to 6 months |

In professional soccer, the average time off for a grade 1-2 injury is 17 days. Returning to sport prematurely is the number one factor in recurrence.

The return to sport should be guided by the achievement of objective criteria, not by a fixed schedule. This approach significantly reduces the risk of recurrence.

How can we prevent repeat offenses?

Prevention is based on eccentric strengthening of the hamstrings, appropriate dynamic warm-ups, and intelligent management of training load. The FIFA 11+ program reduces hamstring injuries by 60%.

| Element | Frequency | Proven benefit |

|---------|-----------|-----------------|

| Nordic hamstring exercise | 2-3 times per week before the season, once per week during the season | Reduces risk by 51% |

| Dynamic warm-up | Before each workout | Better than static stretching |

| Load monitoring | Continuous | Optimal ratio: 0.8-1.3 |

| Eccentric force | Maintain >337N | Protective threshold identified |

• Maintain a hamstring-to-quadriceps strength ratio greater than 0.6.
• Monitor your fatigue (effort perception scale, sleep quality)
• Don't neglect the preseason to develop eccentric strength
• Avoid sudden increases in training volume or intensity.

Key points to remember

• Hamstring strains are a common but treatable injury.
• A history of injury is the main risk factor for recurrence.
• The PEACE and LOVE protocol guides modern treatment
• The return to sport must be based on objective criteria, not on a calendar.
• The Nordic hamstring exercise reduces the risk of injury by 51%.