Influence of Fast and Slow Imagined Muscle Contractions on Muscle Function or Central Nervous System Properties

Participants will complete 4 laboratory visits in a randomized order, including a familiarization session, a control condition, and 2 conditions involving imaginary muscle contractions. During visits involving imaginary muscle contractions, participants will complete 2 sets of 25 repetitions of either fast (i.e., less than 1 second to peak torque increase torque as fast as possible) or slow (i.e., 3 seconds to peak torque) isometric elbow flexions. Before and after each condition, single-pulse transcranial magnetic stimulation will be delivered to the primary motor cortex to measure the amplitude of motor-evoked potentials and the duration of the resulting silent periods in the bicep brachii to quantify changes in corticospinal excitability and inhibition, respectively. Rapid maximal voluntary isometric contractions will be used to measure changes in rate of torque development, peak torque, and rate of muscle activation.