THE UTILITY OF HEART RATE AND RPE IN DETERMINING OXYGEN UPTAKE DURING HIGH-INTENSITY EXERCISE

PURPOSE The purpose of this study was to determine whether exercise protocols based on heart rate (HR) and ratings of perceived exertion (RPE) elicited steady-state oxygen uptake (VO2) during high-intensity aerobic exercise. METHODS Nine sedentary males (age = 23.9 ± 4.6 years, height = 177.4 ± 10.1 cm, weight = 75.28 ± 12.95 kg) completed three 15-minute submaximal exercise cycle ergometer tests based on: 1) constant power output (PO) corresponding to 75% VO2 max (PO75), 2) HR corresponding with 75% VO2 max (HR75), and 3) RPE corresponding with 75% VO2 max (RPE75). VO2, HR, RPE, and blood lactate concentration [La−] levels were measured during all tests. A two-factor repeated measures ANOVA was used to compare VO2, HR, RPE, and [La−] at minute 3 and end-exercise across tests. A one-way repeated measures ANOVA was used to compare end-exercise PO for the three tests. Post-hoc means comparisons were performed using a Fisher's LSD test. A priori significance was established at P <0.05. RESULTS End-exercise VO2 was significantly higher than the respective minute 3 VO2 for the PO75 (3 min VO2 = 2.22 ± 0.29 L·min−1; end-exercise VO2 = 2.59 ± 0.29 L·min−1) and RPE75 tests (3 min VO2 = 2.24 ± 0.26 L·min−1; end-exercise VO2 = 2.40 ± 0.44 L·min−1), but not the HR75 test (3 min VO2 = 2.26 ± 0.31 L·min−1; end-exercise VO2 = 2.36 ± 0.37 L·min−1). End-exercise VO2 was significantly greater for the PO75 test than both the RPE75 and HR75 tests, but there was no significant difference between end-exercise VO2 for the RPE75 and HR75 tests. No significant differences were observed between the three tests for VO2 at minute 3. Nor were any differences observed for end-exercise [La−] between the tests (PO75 [La−] = 7.38 ± 1.60 mmol·l−1; HR75 [La−] = 7.66 ± 2.37 mmol·l−1; RPE75 [La−] = 7.48 ± 2.63 mmol·l−1). CONCLUSION Exercise prescriptions based on HR and RPE are equally effective at reducing the slow component of VO2 that occurs during high-intensity exercise.