Moderate Intensity Cycling Exercise after Upper Extremity Resistance Training Interferes Response to Muscle Hypertrophy but Not Strength Gains

The purpose of the present study was to examine the effect of 30-min moderate intensity cycling exercise immediately after upper-body resistance training on the muscle hypertrophy and strength gain. Fourteen subjects were randomly divided between two groups. One group performed moderate intensity (55% of maximum oxygen consumption [VO2max], 30 min) cycle training immediately after arm resistance training as concurrent training (CT; n = 7, age: 21.8 +/- 0.7 years, height: 1.68 +/- 0.06 m, weight: 60.3 +/- 7.4 kg); the second group performed the same endurance and arm RT on separate days as control group (SEP; n=7, age: 22.1 +/- 0.7 years, height: 1.76 +/- 0.05 m, weight: 63.8 +/- 3.6 kg). The supervised progressive RT program was designed to induce muscular hypertrophy (3-5 sets of 10 repetitions) with bilateral arm-curl exercise using 75% of the one repetition maximum (1RM) with 2-min rest intervals. The RT program was performed for 8 weeks, twice per week. Muscle cross-sectional area (CSA), 1RM, and V-O2max were measured pre- and post-training. Significant increases in muscle CSA from pre-to post-training were observed in both the SEP (p = 0.001, effect size [ES] = 0.84) and the CT groups (p = 0.004, ES = 0.45). A significant increase in 1RM from pre-to post-training was observed in the SEP (p = 0.025, ES = 0.91) and CT groups (p = 0.001, ES = 2.38). There were no interaction effects (time x group) for CSA, 1RM, or V-O2max. A significantly higher percentage change of CSA was observed in the SEP group (12.1 +/- 4.9%) compared to the CT group (5.0 +/- 2.7%, p = 0.029), but no significant difference was observed in the 1RM (SEP: 19.8 +/- 16.8%, CT: 24.3 +/- 11.1%). The data suggest that significant improvement of CSA and strength can be expected with progressive resistance training with subsequent endurance exercise performed immediately or on a different day. Changes in CSA might be affected by subsequent cycling exercise after 8 weeks of training.