Is Oxygen Uptake Measurement Enough to Estimate Energy Expenditure During High-Intensity Intermittent Exercise? Quantification of Anaerobic Contribution by Different Methods.

Purpose: The aim of the present study was to compare the contributions of the anaerobic pathway as determined by two different methods and energy expenditure during a typical high-intensity intermittent exercise (HIIE) protocol. Methods: A descriptive research design was utilized in which thirteen physically active men performed six experimental sessions consisting of an incremental test (session 1), submaximal tests at 40, 50, 60, 70, 75, 80, 85, 90% of velocity associated with maximum oxygen uptake (v V˙ O2max) with two intensities per session (sessions 2-5), and the HIIE protocol (session 6; 10 efforts of 1 min at v V˙ O2max interspersed by 1 min of passive recovery). The estimation of anaerobic energy system contribution was calculated by: (a) the excess post-exercise oxygen consumption plus delta lactate method and (b) the accumulated oxygen deficit method using the difference between predicted oxygen demand from the submaximal tests of varying intensities and accumulated oxygen uptake during HIIE. Estimation of aerobic energy system contribution was calculated through the measurement of oxygen consumption during activity. Total EE during the entire HIIE protocol (efforts + recovery) and for the efforts only were calculated from each method. Results: For efforts + recovery and efforts only, anaerobic contribution was similar for both methods, and consequently total EE was also equivalent (p = 0.230 for both comparisons). During efforts + recovery, aerobic:anaerobic energy system contribution was (68 ± 4%: 32 ± 4%), while efforts only was (54 ± 5%: 46 ± 5%) with both situations demonstrating greater aerobic than anaerobic contribution (p < 0.001 for both). Conclusion: Anaerobic contribution seems to be relevant during HIIE and must to be taken into account during total EE estimation; however, the type of method employed did not change the anaerobic contribution or total EE estimates.

Reduced leptin level is independent of fat mass changes and hunger scores from high-intensity intermittent plus strength training.

BACKGROUND: This study aimed to analyze the effects of high-intensity intermittent training (HIIT) plus strength training on body composition, hormone related to energy balance (leptin), and hunger scores in physically active non-obese men. METHODS: Sixteen men were allocated in two different groups, training group (N.=10) performed a combined HIIT (5 km, 1 minute of effort interspersed by 1 minute of rest in passive recovery) followed by strength exercise session (three sets, with load of 8-12 repetition maximum) twice a week, during 8 weeks, while control group (N.=6) did not suffer any intervention. Hunger scores, leptin concentrations and body composition were assessed. Body composition, fasting leptin and hunger score were compared through two-way analysis (group and period) with repeated measures in the second factor while leptin and hunger scores in exercise session pre- and post-8 weeks through two-way analysis (period and time of measurement) with repeated measures in the second factor. RESULTS: The fasting leptin decreased pre- to post-8week in training group (7.7±4.9 to 2.9±2.1 ng/mL; P=0.012). For leptin response to exercise session there was main effect of training period, with higher values pre- (6.5±3.9 ng/mL) than post-training (2.6±2.1 ng/mL; P<0.001). For hunger scores there was effect of time of measurement (P<0.001), decreasing after breakfast and increasing over the experiment. CONCLUSIONS: Combined HIIT plus strength training were able to promote alterations in a hormone related to energy balance independent of body composition and hunger index alterations in physically active non-obese men.