Abstract

Neural activation (IEMG) was measured in fatigued and non-fatigued conditions during 100 m and 400 m runs. Three male sprinters served as subjects. The runs were filmed with two Locam 51-0003 cameras set to operate at 100 frames per second and with a JVC video cassette system. Maximum and minimum IEMG (MAXA and MINA) of five leg muscles was recorded telemetrically during contact and flight phases triggered by an electrical signal. It was telemetered by the strain gauge plates in the spike shoes. Muscular relaxation was determined using MAXA and MINA. Blood samples were drawn from the fingertip to determine peak lactate concentration following each run. The average velocity was 7.1 greater in supramaximal running with a towing system than in normal maximal running during the 100 m sprint. MAXA decreased 5.2 in the fatigued conditions of short runs with decreasing velocity (5.6). Whereas in the 400 m run MAXA increased 23.4 with decreasing velocity (15.0). It was concluded that the difference in maximal neural activation between short and long sprint running with increasing fatigue can be explained by the intensity of the effort (maximal vs submaximal). The primary reasons for fatigue in both sprint events are most likely in skeletal muscles not in central nervous system or in neuromuscular transmission. Verf.-Referat