Abstract des Autors

We have studied the participation of anaerobic metabolism to the energy requirement according to the duration and intensity of exercise. We have measured blood lactic acid concentration and pH (arterialized blood) and Na+ and K+ (veinous blood) after a short duration of supra maximal treadmill running. We have defined 20 situations through 5 durations (30, 45, 60, 75 and 90 s) and 4 intensities (100, 115, 130 and 140 of the speed corresponding to VO2max). Each subject performed 13 different situations in randomized order. Every test was made on the same weekday, for 4 months. The subjects were 9 long-distance runners (average training 100 km/wk for a minimum of 2 years). The results show that increasing intensity and/or duration of exercise increases the variation of lactate and pH significantly. This study also confirms that anaerobic metabolism may produce energy up to 90 s after the beginning of exercise. Plotted against time, the increase of lactate (DLAC/T) for a given intensity is relatively steady when time increases, but for the longest duration where it decreases. For a given duration, lactic metabolism energy release is more important when intensity increases. When expressed in terms of blood lactate increase rate (DLAC(n)-DLAC(n-1)/15s), maximal values are obtained for two situations: 130-60s and 140-30s. Considering ions, especially K+, our results show only a small increase in veinous blood, but are consistent with Sjogaards observations. Verf.-Referat (gekuerzt)