Ventilatory threshold (VT) is one of the best indexes of aerobic fitness, but its evaluation is laborious and expensive. The High Frequency (HF) component of the heart-rate spectrum is influenced by ventilation: thus, changes in the HF component during exercise might reflect the ventilatory adaptations occurring at VT. Eleven subjects with different aerobic fitness levels were enrolled. RR time series were recorded during an incremental ergometric exercise. VT{sub}2 (uncompensated ventilatory threshold) was identified by averaging the values from 2 traditional methods based on gas analysis and visual inspection of the ventilatory curve, and from the detection of a deflection point in respiratory sinus arrhythmia from the R-R interval spectrum. The agreement between the two methods of VT detection was high (mean percentage error=5%). Our results may provide a new simple and inexpensive method to detect VT during an exercise test based on heart rate data.
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