'WARM-UP' EFFECTS ON FREQUENCY CONTENT OF EMG IN DYNAMIC EXERCISE: IMPLICATIONS FOR ASSESSING FATIGUE

Abstract

The purpose of this study was to examine the implications of the increasing muscle temperature that occurs during dynamic exercise for using the frequency content of EMG for assessing muscle fatigue in such activities. It is known that the temperature of the active muscles can be elevated to around 40°C during prolonged exhaustive exercise (Saltin et ai, 1972) and that temperature changes can affect the frequency content of surface EMG (Merletti et ai, 1984). Several of the previous studies in this area have shown initial increases in median frequency (fmed) prior to a decline with fatigue where the activity was not proceeded by other exercise (Jansen et ai, 1997, Gosselin et ai, 2000, Hausswirth et ai, 2000). It is hypothesised that these initial rises are due to increasing muscle temperature and that this may affect the accurate measurement of fatigue.