Qualitative and quantitative situational characteristics of muscle strains in sports: a systematic review and meta-analysis.

Muscle strains such as hamstring, adductor, calf, and rectus femoris injuries are common in sport, but the exact body positions and movements that precede the moment of injury have been hard to pin down. This review pooled findings from studies that used video recordings to analyse the situational characteristics of 728 muscle strains occurring without direct contact from another player or object. The pooled evidence found that most injuries happened during running or during sport-specific manoeuvres involving active muscle contraction combined with lengthening of the muscle-tendon unit, and that non-contact mechanisms were more frequent than indirect contact ones.

Distinct patterns emerged by muscle group, for example hamstring injuries tended to occur with the knee near full extension and the hip flexed, while calf injuries involved ankle dorsiflexion with the knee close to extension. The main limitation is that this is observational video analysis across a modest number of studies, so it describes associated injury patterns rather than proven causes.

If you have ever pulled a hamstring or calf muscle while running or changing direction, you might wonder whether there is a typical way these injuries happen. This review gathered video-based studies that captured the actual moment athletes sustained muscle strains, covering 728 injuries in total, to look for common patterns in body position and movement just before injury. The researchers found that most of these injuries were not caused by someone else touching or colliding with the athlete.

Instead, they happened during running or specific sporting movements where a muscle was actively contracting while also being stretched. Different muscles showed different patterns.

Hamstring injuries often occurred with the knee nearly straight and the hip bent, adductor injuries involved the hip extending, moving outward, and rotating, and calf injuries involved the ankle bending upward with the knee nearly straight. It is important to understand that this study describes patterns seen on video, not a guaranteed cause of every strain, and the number of underlying studies was still relatively small. It does not tell us how to prevent these injuries, only what tends to be happening physically right before they occur.

This is a summary of research, not medical advice. Talk to your own healthcare provider about anything affecting your care.

This systematic review and meta-analysis pooled 21 studies using video analysis to characterise the situational mechanics of 728 indirect and non-contact muscle strains across sports. Non-contact mechanisms accounted for 74% of injuries versus 26% classified as indirect contact, and most injuries clustered around running or sport-specific manoeuvres involving muscle-tendon unit lengthening under active contraction, consistent with an eccentric loading pattern rather than acute traumatic contact. Muscle-group-specific kinematic patterns were identified.

Hamstring injuries were characterised by a knee position close to extension, with the underlying movement transitioning from flexion to extension, alongside a flexed hip with variable movement direction. Adductor injuries involved rapid muscle lengthening driven by hip extension, abduction, and external rotation.

Rectus femoris injuries combined hip flexion with knee extension movement, and calf injuries involved ankle dorsiflexion exceeding 10 degrees at the presumed injury moment with the knee near extension. Because this evidence derives from retrospective video analysis of naturally occurring injuries rather than controlled biomechanical testing, causal inference about injury mechanism is limited, and heterogeneity across sports, camera angles, and injury definitions likely affects precision. The findings describe recurring situational patterns rather than establishing modifiable risk factors or informing specific prevention strategies.