Postural control and neuromuscular activity during the performance of functional stability tests in individuals with and without risk of lower limb injury

Abstract

Introduction: Dynamic postural stability tests were frequently used in pre-session period to assess musculoskeletal injury risks in physically active and athletes persons. However, there are little information about the specifics of neuromuscular activation pattern related to lower performance in such tests. Objective: The aim of the study is to investigate the postural sway profile and the neuromuscular activation pattern during dynamic stability tests. Methods: Twenty-six (15 males) healthy and physically active individuals perform the Y Balance Test (YBT) under a force platform, while EMG activity from tibialis anterior (TA) and gastrocnemius medialis (GM) muscle were acquired. Data from the anterior direction reach task were used to classify the individuals (high risk, N=8; low risk, N=18), for determine the lower limb with high- and low-performance in YBT, and for signal analysis. Descriptive measures of postural sway, in terms of center of pressure (COP) coordinates, EMG fluctuations and EMG-COP temporal association were calculated. Two-way mixed model ANOVA (group versus lower limb) were used for statistical analysis, assuming a threshold of 5%. Results: There was a significant between-group difference for the LPL (63±3 vs. 67±5%, high-risk vs. low-risk, respectively; t=-2.162, P=0.044, d=0.860) but not for HPL (68±4 vs. 68±5%; t=0.009, P=0.993, d=0.004). Overall, the LPL of the high-risk group exhibited lower TA-anterior COP association (F=4.421; P=0.046; η2=0.156), larger GM-lateral COP temporal delay (F=7.528; P=0.011; η2=0.239) and a strong TA-lateral COP anti-phase association (F=7.267; P=0.013; η2=0.232). Conclusion: More than postural sway profile, the neuromuscular activity pattern from the low-performance limb and the high risk group showed remarkable changes, indication a potential disruption in the stabilization function of ankle joint, mainly in the lateral axis, which could be one of the factor related to lower limb injuries.