Abstract

Recently, Conconi et al. proposed that the point where heart rate departs from linearity in an incremental exercise test is a good predictor of the aerobic threshold (AeT). We hypothesized that this heart rate break point (BrP) is a better predictor of the anaerobic threshold (AnT). To test this hypothesis, 11 subjects with different levels of conditioning were tested on a cycle ergometer using a progressive incremental exercise protocol. Heart rate from EKG tracings and blood samples for lactate determination were taken every minute. The results showed the following significant correlation coefficients when the variables were expressed in watts: AeT and AnT = 0.92; AeT and BrP = 0.89; AnT and BrP = 0.97. The AeT was significantly lower than the BrP. There was no significant difference between the AnT and BrP. Another group consisting of 16 subjects performed two tests to evaluate the reproducibility of the BrP. Although a ventilatory AnT was noted in all the tests, eight subjects failed to demonstrate a BrP in at least one of the evaluations. We conclude that the BrP may coincide with the AnT and not the AeT; however, the fact that the BrP could not be demonstrated with a documented ventilatory AnT in several subjects suggests that no causal relationship exists between the two. Verf.-Referat