Electromyography
bipolar
CONTRACTION
Quadriceps electromyogram (EMG) was recorded from the right rectus femoris (RF) using monitoring electrodes with full-surface solid adhesive hydrogel (Delsys Trigno Wireless EMG, Natick, MA, USA) with on-site amplification. Electrodes were placed in a bipolar electrode configuration on the midpoint of the RF with an inter-electrode distance of 100 mm. The EMG electrode was placed in the same location during all visits. The surface EMG electrodes were used to assess the maximal EMG of the RF during a maximal voluntary contraction before each TTE. RF EMG was continuously measured during the subsequent time trial to estimate changes in central neural command.All EMG recordings were high-pass filtered using fourth order zero-lag Butterworth filters and subsequently smoothed using a root-mean-square (RMS) filter (30-ms symmetrical moving window with successive 1-ms steps). EMG signal amplitudes from the TTE were normalized to the maximum RMS EMG amplitude recorded during MVC testing of the quadriceps. The EMG amplitudes during the TTE were measured over five seconds at baseline and then measured as an average of 0–20%, 20–40%, 40–60%, 60–80%, and 80–100% based on the shorter trial. Due to recording issues (i.e. electrode falling off/coming loose, etc.), data from six participants were excluded from analysis.