THE EFFECTS OF MUSCULAR FATIGUE ON THE COORDINATION OF A MULTIJOINT MOVEMENT IN HUMAN

The purpose of the present experiment was to investigate the adaptatio n to fatigue in a multijoint movement. The subjects' task was to throw a ball towards one of three targets in two conditions of no fatigue a nd fatigue. Results showed that the number of successful trials decrea sed with fatigue. Analysis of these successful trials showed that, wit hout fatigue, the final hand velocity resulted from a 'summation of sp eed' principle from the elbow to the hand joint. With fatigue, a new i nter-segmental organization was necessary in order to maintain a good motor performance. This compensating strategy was characterized by the absence of a temporal delay between the elbow and hand peak velocity suggesting that, with fatigue, movement organization was similar to th at of a rigid system. In other words, the 'summation of speeds' princi ple was no more respected. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.