Alterations in anaerobic threshold as the result of endurance training and detraining.

The response of anaerobic threshold (AT) to endurance training and detraining was studied in 21 males (mean age = 25 yr). Members of the exercise group trained on a cycle ergometer at 80% of maximal oxygen uptake (VO2max) for 30 min four times per week for 9 wk. Nine weeks of detraining followed. A step-wise incremented cycle ergometer test was used to measure maximal and submaximal values of metabolic variables at 3-wk intervals. The criterion for determination of the onset of metabolic acidosis was a systematic increase in the ventilatory equivalent for O2 (VE/VO2) without an increase in the ventilatory equivalent for CO2 (VE/VCO2). Significant increases and decreases of VO2max for the exercise group during training and detraining, respectively, were revealed by ANOVA. Following 9 wk of training, elevations of 70.4% and 19.4% had occurred in AT expressed as absolute VO2 (AT l . min-1) and percent of VO2max (AT-VO2), respectively. The latter change was not statistically significant. Losses of training gains in AT (l . min-1) were significant after 6 and 9 wk of detraining. The results of this study indicate that 9 wk of training is of sufficient duration to cause a significant alteration in AT. Loss of this training gain occurs rapidly and appears to be similar to changes in VO2max.