Metabolic Effects of Two Novel High-Intensity Circuit Training Protocols

Abstract

Circuit weight training (CWT) and high-intensity interval training (HIIT) are two popular exercise formats for stimulating both aerobic and anaerobic benefits in a time efficient manner. While some research has established the benefits of both formats, no research has determined if performing HIIT prior to CWT (HICWT) has a different acute response compared to integrated HIIT with mini-CWT (three-exercise clusters; TRIIT). PURPOSE: To examine the physiological effects [energy expenditure (EE), oxygen consumption (VO ), heart rate (HR), blood lactate (BLa-), blood pressure (BP), excess post-exercise oxygen consumption (EPOC)] and rating of perceived exertion (RPE) of the sequence order of HIIT with CWT. METHODS: Fourteen trained men (25.7 ±4.4 yr) completed two separate (by ≥72 hrs) resistance exercise protocols matched for time and load. Both protocols consisted of six HIIT bouts and three sets of nine exercises (50% one-repetition maximum) in a CWT or mini-CWT format. Oxygen consumption, HR and EE were monitored throughout the protocols, while EPOC, BLa- (five time points), BP (four time points) and RPE were measured post-exercise. RESULTS: Oxygen consumption (1.991 ±0.224 vs. 1.923 ±0.225 L/min, p=.024), EPOC (62.0 ±7.8 vs. 57.0 ±6.2 kcal, p=.034) and EE (435 ±48.8 vs. 420 ±49.0 kcal, p=.012) was significantly higher during the HICWT compared to the TRIIT protocol. BLa- was significantly higher at all post-exercise time points (immediate post, 5 min, 10 min and 20 min post-exercise) following the HICWT compared to the TRIIT protocol. Mean values for HR and RPE were similar (p>.05) for both protocols. CONCLUSION: Performing HIIT prior to CWT elicits higher metabolic perturbation compared to the integration of HIIT with mini-circuits. HICWT also required greater energy requirements during and after the protocol compared to TRIIT. However, there may not be a practical difference given the protocols only differed by ~25 kcal.