Effect of resistance exercise volume and complexity on EMG, strength, and regional body composition

This study was designed to examine the effects of a 12-week resistance training program using single versus multiple sets of a complex versus simple exercise on EMG, strength and regional body composition. Twenty-eight untrained men (n=15) and women (n=13) performed resistance training twice per week. Group 1 (S-1, n=9) performed one set of a leg press (LP) and bicep curl (BC) exercise, group 2 (M-6, n=9) performed six sets of a LP and BC exercise, and group 3 (C, n=10) was the control group. One-repetition maximums (1RMs) and EMG were measured in the LP and BC during pre-, mid-, and post-training. Lean body mass of the legs and arms were measured pre- and post-training by dual energy X-ray absorptiometry. Results of the study indicated that both S-1 and M-6 groups significantly increased percentage strength pre- to post-training in both the LP and BC [S-1 pre-/post-LP=41.2 (23.7)%, BC=8.5 (6.71)%; M-6 pre-/post-LP=52.6 (12.6)%, BC=22.8 (15.6)%; mean (SD)]. However, compared to S-1, M-6 showed a significantly greater increase in percentage strength in the BC (P≤0.05) from pre- to post-testing. Results also showed that M-6 produced a significant increase in biceps (single-joint) muscle EMG values pre- to mid-testing compared to S-1. There were no significant differences found in lean muscle mass gains for the legs or arms in either training group. The data from this study suggest that multiple sets produce a greater increase in percentage strength gain for a simple exercise. It is possible that some type of neural mechanism is responsible for the observed difference.