Knight, C. A., & Kamen, G. (2001). Motor unit discharge behavior during 10% MVC isometric contractions following resistance exercise training in young and older adults. Medicine and Science in Sports and Exercise, 33(5), Supplement abstract 1214.

This study determined whether a resistance-training program would alter motor unit firing rates, recorded during low force isometric contractions in young and older adults. Young men (N = 8) and older men (N = 7) were assessed for maximal knee extensor torque and motor unit discharge rate on each of four occasions. Progressive resistance training using both isometric and dynamic 10-RM contractions began immediately after the second testing. Further tests were conducted after two and six weeks of resistance training.

Exercise training produced similar improvements (34%) in extensor torque in both age groups. Motor unit firing rates remained relatively constant during resistance training.

Implication. Motor unit discharge rates are specific to tasks requiring high levels of muscular force. Resistance training on different exercises does not affect them.

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