POSITION SENSE AT THE ELBOW AFTER FATIGUING CONTRACTIONS

Fatigue is often associated with increased clumsiness. One possible ex planation for this is that the proprioceptive signals from receptors i n and around muscles change during muscle fatigue. Thirteen human subj ects were tested for their ability to match the elbow angle of one arm with the contralateral arm, before and after a fatiguing contraction of one arm. Contractile fatigue was induced by a series of maximal vol untary contractions of the elbow flexors of the dominant arm. While fa tigue of either the target arm or the matching arm usually changed the ability of individual subjects to match arm position, this effect var ied markedly from one subject to another and no consistent pattern was discerned. In particular, there was no reciprocal change when the fat igued arm was the matching arm compared with when the non-fatigued arm was the matching arm. The absence of a consistent reciprocal effect i ndicates that the fatigue-related changes in the ability to match arm position are not solely due to changes in proprioceptive signals and t hat central fatigue processes are probably involved.