Validity of a Muscle Specific Method to Evaluate the Anaerobic Threshold in Exercised Muscles

Resumo

The goal of this study was to describe and validate a muscle specific method to evaluate the anaerobic threshold in a working muscle based on the simultaneous measurement of EMG activity and the deoxyhemoglobin content (AT_HHb-EMG). The study involved males with different fitness levels. During the cycling (n = 40) and ski double poling (n = 9) incremental ramp tests, blood lactate concentration, and muscle deoxyhemoglobin content and EMG activity were measured. Some participants were involved in the cycling test-retest study (n = 11). In cycling and double poling tests, close and significant correlations (r = 0.89 – 0.92, P < 0.002) were found between lactate threshold (a marker of the anaerobic threshold at the organism level) and the AT_HHb-EMG (a marker of the AT at the working muscle level). The coefficient of variation of the AT_HHb-EMG in the cycling test-retest was low (~3%). The muscle specific AT_HHb-EMG demonstrates low variability and is appropriate to detect the fitness level and training-induced increase in aerobic performance in a working muscle. The emergence on the market of miniature EMG amplifiers and near-infrared spectrometers opens wide possibilities for using our method in laboratory studies and in field tests.