A: randomized, crossover design of experiment 1 assessing voluntary activation before and after a 2-min maximal voluntary contraction (MVC) (VOL; top) or electrically stimulated maximal contraction (STIM; bottom). Individuals performed 5 brief MVCs with superimposed twitches followed by a resting twitch (not shown) before the fatiguing task. These brief MVCs were then repeated at 5, 20, 40, 60, 90, 120, 240, 360, 480, and 600 s after the fatiguing contraction. B: randomized, crossover design of experiment 2 assessing the effects of 2-min MVC (VOL; top) or electrically stimulated maximal contraction (STIM; bottom) on motoneuron excitability and specifically F-waves. Two baseline sets of 60 F-waves (2 sets of 30 F-waves separated by 1 min) were performed 5 min apart before the fatiguing task. Immediately following the fatiguing tasks, sets of 30 F-waves (0.5 Hz) were recorded at 0–60, 90–150, 210–270, 330–390, 450–510, and 570–630 s after the fatiguing contraction to match the time points in experiment 1.