High-intensity interval training (HIT) has demonstrated similar cardiovascular and metabolic adaptations versus endurance training (Burgomaster et al., 2008). Few studies, however, have investigated acute physiological changes during HIT.
PURPOSE: The aim of this study was to compare acute changes in heart rate (HR), blood lactate (BL), oxygen uptake (VO2), calorie expenditure, affect, and rating of perceived exertion (RPE) during two different intensities of HIT.
METHODS: Active adults (four women and eight men, age = 24.17 ± 6.25 years) initially performed a VO2max test to determine workload for two different intensities of HIT. The sprint interval training session (SIT) consisted of eight 30-second bouts of all-out cycling at 130% of maximum watts separated by 90 s of active recovery. HIT consisted of eight 60 s bouts at 85% of maximum watts interspersed by 60 s of recovery. Session order was randomized across subjects. Heart rate, VO2, BL, affect, and rating of perceived exertion were continuously assessed throughout exercise.
RESULTS: Repeated measures ANOVA revealed a significant difference between HIT and SIT for VO2 (p<0.001), RPE (p=0.03), and blood lactate (p=0.049). Conversely, there was no significant difference between regimens for HR (p=0.49) or affect (p=0.12). There was a significant difference (p=0.002) in calorie expenditure between regimens.
CONCLUSIONS: During HIT, subjects burned significantly more calories and reported lower exertion than SIT. The higher VO2 and lower BL in HIT versus SIT reflected dissimilar metabolic perturbation between regimens, which may elicit unique adaptations long-term. Although not reflected in the results, six subjects insisted they preferred SIT versus HIT. Therefore, the preferred HIT regimen varies between persons and is dependent upon personality and potentially muscle fiber type. However, if an individual is seeking to burn more calories and to perceive less exertion during exercise, HIT is the recommended routine.