Aerobic and anaerobic thresholds as tools for estimating submaximal endurance capacity

Submaximal endurance capacity was measured and evaluated by the aerobic and anaerobic thresholds, which were determined by using various methods. The reliability of both thresholds and the validity of the anaerobic threshold were evaluated. The theoretical bases of using these thresholds as endurance indices were analysed by a factor model. Further, a function between endurance time, i.e., cycling time to exhaustion, and the exercise intensity related to the anaerobic threshold was constructed and examined. The results of the hypothetical factor model and the results concerning the validity and/or the reliability of the threshold indices suggested that the aerobic and the anaerobic thresholds are appropriate indicators of submaximal endurance in untrained or non-endurance trained men. All threshold indices of this study correlated strongly with each other, with the maximal oxygen uptake and with the anaerobic threshold fixed at blood lactate level of 4 mmol ‧ I-1. The last mentioned was not shown to be a theoretically valid index. The threshold indices reflected muscle metabolic profile to a great extent. The exercise intensity related to the anaerobic threshold significantly explained endurance time in the exponential function, but an improved prediction power could be obtained by multiple regressions including, besides the relative exercise intensity, also muscle fibre composition and initial blood lactate level, or relative muscle glycogen depletion during exercise.