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

Fatiguing concentric (CON) muscle actions of the leg extensors have been shown to result in differences in percent (%) decline in torque for CON, eccentric (ECC), and isometric (ISO) muscle actions. However, the effects of CON fatigue of the forearm flexors on CON, ECC, and ISO torque have not been well established. The purpose of this investigation was to determine the effects of 50 maximal CON isokinetic forearm flexion muscle actions on CON, ECC, and ISO torque. Sixteen adults (8 men (mean ± SD = 23.1 ± 2.3) and 8 women (mean ± SD age = 22.8 ± 1.4)) volunteered to perform 50 consecutive, CON forearm flexion muscle actions at 180° x [s.sup.-1]. Before and after the fatiguing workbout, peak torque was measured (randomly ordered) for CON, ECC, and ISO muscle actions. Polynomial regression analysis indicated a cubic ([R.sup.2] = 0.98) pattern of response during the 50 CON muscle actions. There were no differences in mean % decline (30%) in torque among the three types of muscle actions. The findings indicate that the CON, ECC, and ISO muscle actions share a common mechanism of fatigue as a result of the fatiguing CON workbout. Key Words: Isokinetics, Fatigue