Frequency-specific modulations of oscillatory neural drives to lower leg muscles during gait with aiding and impeding...

Gait training with impeding horizontal force around the center of mass (COM) improves gait speed due to enhancements on activities in gastrocnemius (GC) muscles; however, the underlying neural mechanisms of these changes remain unclear. This study aimed to examine the influence of impeding horizontal force around the COM during gait on oscillatory neural drives to lower leg muscles using coherence analysis of paired surface electromyography, which in the alpha and beta bands reflect subcortical and cortical origins, respectively. Twenty healthy young adults participated in three gait conditions: normal gait without additional horizontal force, and gait with aiding and impeding horizontal forces, which were applied with a load of 5 % of body weight at the second sacral spine level via a waist belt. Medialis and lateralis GC intermuscular coherence in the alpha band (7.5-15 Hz) was significantly higher under the impeding force condition compared to the aiding force and normal gait conditions, whereas beta-band (15-35 Hz) coherence was significantly higher in the impeding force condition only compared to the aiding force condition. Impeding horizontal force around the COM during gait enhances oscillatory neural drives, predominantly from subcortical origins to GC muscles, with additional cortical contributions.