The effects of intermittent isometric fatigue on concentric, eccentric, and isometric torque

Fatiguing intermittent isometric (ISO) muscle actions of the leg extensors have been shown to result in a similar percent (%) decline in torque for concentric (CON), eccentric (ECC), and ISO muscle actions. However, the effects of intermittent ISO fatigue of the forearm flexors on CON, ECC, and ISO torque, have not been established. The purpose of this investigation was to determine the effects of 50 maximal, intermittent ISO forearm flexion muscle actions on CON, ECC, and ISO torque. Twenty adults (10 men (mean ± SD age = 21.9 ± 2.3 years) and 10 women (mean ± SD age = 22.7 ± 2.6 years) volunteered to perform 50 consecutive, intermittent ISO forearm flexion muscle actions. Before and after the fatiguing workbouts, peak torque (PT) was measured (randomly ordered) for CON, ECC, and ISO muscle actions. Polynomial regression analysis indicated a quadratic (R2 = 0.97) pattern of responses during the 50 intermittent ISO muscle actions. There were no differences in mean % decline (29%) in torque values among the three types of muscle actions. The current findings indicate that the CON, ECC, and ISO muscle actions share a common mechanism of fatigue as a result of the fatiguing intermittent ISO workbout. Adviser: Terry J. Hous