Muscle function of the lower limb—Do we really test what we are looking for?

Established measures of lower-limb muscle function repeatedly show weak, inconsistent or absent association and predictive value for injury, re-injury and other musculoskeletal complaints. Progress in prevention, rehabilitation, and return-to-sport decision-making is unlikely to come from recombining or modifying them. The question is whether the quantity they capture is unsuitable-calling for a change in what is measured. Muscle-function assessment should match the demand it sets out to capture: non-contact injuries occur when muscles must stabilise a joint and adapt to a rising external load. This adaptive, stabilising control is largely unaddressed by established measures. Shifting the focus from muscle strength to muscle stability-from producing force against a resistance to holding a position while adapting to a rising external load (Adaptive Force)-may bring assessment closer to what actually determines joint protection and clinical outcome.