title: Electromyographic analysis of movement following a maximal isometric contraction.
abstract: A post-contraction sensory discharge effect following an isometric contraction is commonly cited as the explanation for perception of movement or distortion of limb proprioception during post-contraction movements. The purpose of this study was to compare motor output of agonist neuromuscular activity between a control positioning movement and a post-contraction movement. Terminal positioning accuracy and electromyographic (EMG) data of the triceps brachii during rapid elbow extension were recorded during normal movements and during movements following a maximal isometric contraction. Separate t-tests revealed the post-contraction positioning resulted in significant undershooting of the target position, and also the integrated EMG (IEMG) for the post-contraction conditions was significantly less than the control condition. No difference was observed in mean peak frequencies between the control and post-contraction conditions. Apparently, the post-contraction target undershooting is a result of less total motor output rather than a change in neuromuscular frequency firing rates.
authors.forename: B R
authors.initials: BR
authors.lastname: Etnyre
authors.forename: B D
authors.initials: BD
authors.lastname: Kelley
mesh_terms: D000293:Adolescent; D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009119:Muscle Contraction