Effect Of High-intensity Resistance Training On Twenty-four-hour Respiratory Quotient

Abstract

PURPOSE: To investigate the effect of high-intensity resistance training (RT) on twenty-four-hour respiratory quotient (24-h RQ) by cross-sectional and interventional settings. METHODS: 1) Sedentary subjects (41.7 ± 9.7 yr, n = 7) and subjects performing habitually high-intensity RT (41.6 ± 6.9 yr, n = 8) participated in the cross-sectional study. Twenty-four-hour energy expenditure (EE) under free living condition was measured by doubly-labeled water (DLW) method, and all meals in 3 days before the chamber measurement were provided to all subjects according to the results from DLW method. Then, 24-h RQ was measured by a metabolic chamber. 2) Fifteen young adults participated in the interventional study. They were randomly divided into control (C) group (20.5 ± 1.2 yr, n = 8) and RT group (20.9 ± 1.8 yr, n = 7). RT group performed high-intensity (80 - 90% one-repetition maximum) RT on 2 days per week for 3 months. Before and after the training period, 24-h RQ was measured by a metabolic chamber under the well controlled-condition. RESULTS: 1) In the cross-sectional study, there was a trend that fat-free mass (FFM) in subjects performing high-intensity RT was larger than that in sedentary subjects. However, no difference was observed in 24-h RQ between two groups. 2) In the interventional study, subjects in RT group significantly (P < 0.05) increased FFM and absolute 24-h EE after the training period. However, there was no significant time-by-group interaction in 24-h RQ. CONCLUSIONS: These results suggest that there is no effect of high-intensity RT on 24-h RQ measured by a metabolic chamber. In other words, although high-intensity RT enhances absolute 24-h EE induced by increasing FFM, it may not lead to the improvement of fat oxidation capacity in human subjects.