A Study on Modes of Sensorimotor Cortex Control of Lower Limb Muscles under Different Support Modes in National Freestyle Skiing Aerial Athletes

Objective: To investigate the brain control characteristics of lower limb muscles under different support modes during static standing balance in freestyle skiing aerial athletes. Methods: Seventeen national freestyle skiing aerial athletes were recruited in this study. The center of pressure(COP), electroencephalograph(EEG), and electromyography(EMG) signals of vastus medial(VM), gastrocnemius lateralis(GL) and anterior tibialis(TA) were simultaneously collected during the single-leg standing balance under soft and firm support surface. During testing, subjects were required to stand in single-leg balance with their eyes open for 30.The corticomuscular coherence(CMC) in the beta-range band(13~30 Hz) and gamma-range band(31~45 Hz) was analyzed during standing balance. Results: 1) The variation of COP in X and Y axis was significantly higher during standing balance on soft support surface than that of firm support surface(P<0.001); 2) When standing on the soft support surface, the EMG amplitude of the three muscles in the lower limb was increased significantly(P<0.05); 3) For CMC, the CMC value of GL muscle in both the beta-range was significantly higher when standing on the soft support surface than that of the firm support surface(P<0.05);moreover, the CMC value of gamma-range band was significantly higher than that of beta-range band(P<0.01). Conclusion: For freestyle aerials athletes, the soft support induces a loss of the center of gravity, accompanied by stronger nerve impulses from the brain and greater neural regulation of the lower limb's anterior tibia and gastrocnemius muscles in the sensorimotor cortex, which improves body balance. Additionally, the gamma-band CMC is higher than beta-band CMC, which may be related to characteristics of lower limb muscles contraction under different support modes and attention during the balance control.