Impact Of Order Of Exercises On Substrate Oxidation In Healthy Men

Abstract

PURPOSE: To examine the impact of order of exercises on substrate oxidation in healthy men. METHODS: Eight healthy men (21.3 ± 0.4 yrs, 171.3 ± 3.5 cm 63.4 ± 3.0 kg, 21.6 ± 0.5 kg/m2) completed two experimental trials: either an aerobic exercise after resistance exercise (RA trial) or an aerobic exercise before resistance exercise (AR trial). In the aerobic exercise, subjects completed 60 min of pedaling exercise at 50 % of VO2max. Resistance exercise (30 min in total) consisted of five consecutive exercises (chest press, lat pull down, shoulder press, leg press, seated rowing), each with 10 repetitions for three sets at 75 % of 1RM. Rest period between resistance exercise and aerobic exercise was 10 min. Subjects sustained sitting position for 60 min after the all exercises. Blood and respiratory gas samples (percentage of fat oxidation evaluated by RER) were collected over experimental period. RESULTS: Blood glucose response did not differ between trials. There were no significant differences in blood lactate elevation in response to resistance exercise between trials. However, blood lactate concentration at 60 min after all exercise was significantly higher in the AR trial than in the RA trial (1.5 ± 0.2 mmol/l in the RA trial vs. 2.8 ± 0.7 mmol/l in the AR trial, P < 0.05). Although there was no significant difference in percentage of fat oxidation during aerobic exercise between trials, resting percentage of fat oxidation after the all exercises was significantly higher in the AR trial than in the RA trial (92.8 ± 26.9 % in the RA trial vs. 99.7 ± 1.1 % in the AR trial, P < 0.05). CONCLUSION: The order of exercise between aerobic and resistance exercises does not affect substrate oxidation during aerobic exercise, but aerobic exercise before resistance exercise enhanced fat oxidation during post-exercise period more so than when resistance exercise precedes aerobic exercise.