Effect of exercise duration during incremental exercise on the determination of anaerobic threshold and the onset of blood lactate accumulation

Summary

To determine the effect of the duration of incremental exercise on the point at which arterial blood lactate concentration (HLa) increases above the resting value (anaerobic threshold: AT) and on the point at which HLa reaches a constant value of 4 mM (onset of blood lactate accumulation: OBLA), eight male students performed two different kinds of incremental exercise. A comparison of arterial HLa and venous HLa was made under both conditions of incremental exercise. The incremental bicycle exercise tests consisted of 25 W increase every minute (1-min test) and every 4 min (4-min test). At maximal exercise, there were no significant differences in either gas exchange parameters or HLa values for the two kinds of incremental exercise. However, the peak workloads attained during the two exercises were significantly different (P<0.01). At OBLA and AT, there were no significant differences in gas exchange parameters during the 1-min and 4-min tests except for the workload (at OBLAP<0.01; at ATP<0.05). When venous blood HLa was used instead of arterial HLa for a 4-min test, AT was not significantly different from that obtained by arterial HLa, but OBLA was significantly different from that obtained by arterial HLa (P<0.05). On the other hand, for the 1-min test, venous HLa values yielded significantly higher AT and OBLA compared with those obtained using arterial HLa (P<0.01).

It was concluded that when arterial blood was used, there was no effect of duration of workload increase in an incremental exercise test on the determination of the AT and OBLA expressed in$\dot V_{O_2 }$. On the other hand, when venous HLa was used instead of arterial blood, these points might be overestimated when a fast increase in workload, such as the 1-min test, is used.