Evaluating the effects of anaerobic threshold on heart rate work rate relationships during incremental exercise in healthy male subjects

Abstract

The purpose of the present study was to determine the effectiveness of work rate to heart rate ratio at the estimated anaerobic threshold (A_T). Thirty male subjects performed an incremental exercise test (15 W/min) until the limit of tolerance was reached. Ventilatory and gas exchange parameters were evaluated breath-by-breath and the heart rate was recorded. A_T was estimated from the work rate heart rate ratio and compared with the V-slope method. A deviation from linearity in heart rate was observed only in 4 subjects (13%) and 3 of them (10%) associated with A_T. All other 26 subjects showed linear increase in heart rate to work rate relationships (87%). The O₂ uptake at the estimated A_T using V-slope break point was found to be 1.95 ± 0.2 L/min (65% of maximal O₂ uptake). Absence of a break point in heart rate work rate relationship (87%) and an extremely low percentage of association in A_T estimation between the Conconi and V-slope methods (10%) may reduce the reliability of the Conconi test. Thus, caution should be taken by investigators using this technique, especially when making important decisions for patients and sports training.

Keywords: O₂ pulse, exercise, fitness.

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