Lower Limb Strength Asymmetries Predicts Perceptions Of Limb Function In University Athletes

Previous musculoskeletal injury is a primary risk factor for future injury in part due to persistent neuromuscular deficits and reduced psychological readiness. Central to the aim of reducing sport injuries and increasing athletic performance, a bio-psycho-social approach to athlete monitoring has been adopted that incorporates both objective measures of neuromuscular function and subjective assessments of psychological readiness such as the Sport Fitness Index (SFI) which quantifies athletes’ perceptions of lower-limb function (perceived-function). However, the relationship between perceived-function and objective functional measures such as the between-limb asymmetry index (AI) remains unknown. PURPOSE: To evaluate the relationship between perceived-function and limb AI across a lower body muscle strength testing battery. METHODS: University athletes (n = 196, females: n = 96) from six high risk sports for lower body injury completed the SFI, maximal countermovement jump (CMJ) testing with extra loads corresponding to 0%, 30% and 60% body mass (n = 5), unilateral CMJ (n = 3) testing, and unilateral repeated hop testing (n = 20) on a dual force plate system. Athletes also performed isokinetic multi-joint eccentric and concentric strength testing in a robotic leg press dynamometer. Between-limb AIs were calculated for each testing condition. Perceived-function in the SFI was rated on a 0-100 scale, to obtain GOOD (SFI >86), FAIR (61 < SFI < 85), and POOR (SFI < 60) perceived-function groups. A cumulative link mixed effects model was used to examine the effects of between-limb AI on perceived-function groups. RESULTS: For every absolute unit increase in isokinetic concentric strength AI and CMJ with 60% body mass concentric impulse AI, the odds of belonging to a lower perceived-function group increased by 1.036 (95% CI: 1.001-1.070) and 1.161 (CI: 1.010-1.336) times; respectively. CONCLUSIONS: Increased concentric muscle strength asymmetries predicted decreased perceived-function in university athletes. By combining introspective measures of limb function such as the SFI along with mechanical muscle function testing, it is possible to achieve an integrated bio-psycho-social approach to preseason testing that may inform targeted intervention protocols to mitigate injury risk on a group level.