Identification of the lactate threshold and the heart rate deflection point by the perceived exertion curve

Abstract

The purpose of this study was to identify the lactate threshold (LT) and the heart rate deflection point (HRDP) by the perceived exertion curve (DmaxRPE). Nine physically active male subjects (weight, 77.3 ± 8.9 kg; height, 177.5 ± 3.2 cm; age, 22.2 ± 2.7 yrs, and body fat, 11.3 ± 5.5%) underwent a progressive treadmill test starting at 6 km·h -1 with 1 km·h -1 increments every 2 min. No significant differences for heart rate (HR), values of perceived exertion (RPE), and intensity of the occurrence of HRDP, DmaxRPE, and LT were found (P≥0.05). Significant correlations of HR, RPE, and intensity of occurrence of HRDP when compared to LT were found (HR, r = 0.90; RPE, r = 0.91; and HRDP, r = 0.91; all P≤0.05). DmaxRPE had low correlations with FC, RPE, and intensity of occurrence of HRDP (HR, r = 0.14; RPE, r = -0.02; HRDP, r = -0.065; all P≥0.05), and also with the LT (HR, r = 0.35; PSE, r = 0.19; LT, r = 0.036; all P≥0.05). The results indicate that DmaxRPE has only reasonable predictive power to determine the LT.