Comparisons of the Metabolic Intensities at Heart Rate, Gas Exchange, and Ventilatory Thresholds

PURPOSE This study compared the VO2 corresponding to the critical heart rate (CHRVO2 ) and the physical working capacity at the heart rate fatigue threshold (PWChrtVO2 ) to the gas exchange threshold (GET), ventilatory threshold (VT), and respiratory compensation point (RCP). METHODS Nine runners (mean ± SD, age 23 ± 3 years) completed an incremental test on a treadmill to determine VO2peak, GET, VT, and RCP. The CHRVO2 and PWChrtVO2 were determined from 4 separate constant velocity treadmill runs to exhaustion and HR and time to exhaustion were recorded. Differences among the thresholds were examined with a one-way repeated measures ANOVA (p ≤ 0.05). RESULTS The GET (38.44 mL×kg-1×min-1, 78% VO2peak), VT (37.36 mL×kg-1×min-1, 76% VO2peak), and PWChrtVO2 (38.26 mL×kg-1×min-1, 77% VO2peak) were not different, but were lower than the RCP (44.70 mL×kg-1×min-1, 90% VO2peak; p = 0.010, p < 0.001, p = 0.001, respectively). The CHRVO2 (40.09 mL×kg-1×min-1, 81% VO2peak) was not different from the GET (p = 1.000), VT (p = 0.647), PWChrtVO2 (p = 1.000), or RCP (p = 0.116). CONCLUSIONS These results indicated that the initial metabolic intensities at CHR and PWChrt lie within the heavy and moderate intensity domains, respectively. Therefore, the PWChrt may provide a relative intensity more appropriate for untrained populations, while the CHR may be more appropriate for more trained populations.