Comparison of two methods for aerobic threshold determination

Summary

A new method of aerobic threshold (AerT) determination, as a minimum of so-called lactate equivalent (Berg et al. 1980; Lehmann et al. 1983), was compared with the generally used method (AerT₁) presented first by Wasserman et al. (1973). The comparison was made with data from 32 subjects in repeated maximal exercise tests on a bicycle ergometer. The AerT as a minimum of lactate equivalent was determined using both a computerized method for curve fitting (AerT₃) and visual inspection (AerT₂).

AerT₂ and AerT₃ showed similarity: the regression coefficient was 0.88 and 0.95 and the correlation coefficient was 0.84 and 0.88 in the first and in the second tests, respectively. AerT₁ and AerT₂ showed similar mean estimated values, but AerT₃ showed slightly higher mean values than AerT₁ (p<0.05 and p<0.01) or AerT₂ (p<0.01). The regression coefficients between AerT₁ and AerT₂ or AerT₃ (0.60–0.71) showed different slopes from the identity (p<0.001). The corresponding correlation coefficients were 0.88 and 0.89 with AerT₂, and 0.75 and 0.79 with AerT₃ respectively in the first and second tests. However, in two thirds of all determinations the difference between these two estimation methods (AerT₁ and AerT₂) was <-0.10 1 O₂·min⁻¹.

In conclusion, AerT as a minimum of lactate equivalent differed slightly from AerT determined using the traditional method. However, its determination criterion is unambiguous and allows objective computerized curve fitting. The physiological correlates of this new AerT index should be studied carefully before final evaluation of its usefulness in applications can be made.