Effects of volume and exercise complexity on neural adaptations, strength gains and lean body mass in untrained adults

Abstract

This study was designed to examine the effects of a 12-week resistance-training program using single vs. multiple sets of a complex vs. simple exercise. Twenty-eight untrained men (n=15) and women (n=13) (mean age 21.6 +/- 2.5) performed several resistance exercises twice per week: a complex movement, the leg press (LP), and a simple movement, the biceps curl (BC). Group one (S-1, n=9) performed one set of each exercise, group two (M-6, n=9) performed six sets of the same exercises, and group three (control, n=10) was the control group. One-repetition maximums 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 (DEXA). 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% +/- 45.6%). However, compared to S-1, M-6 showed a significantly greater increase in percentage strength in the BC (p=0.05) from pre- to posttesting. Results also showed that M-6 produced a significant increase in biceps (single-joint) muscle EMG adaptations pre- to mid-testing (p=0.05) compared to S-1. There were no significant differences found in lean muscle mass percent increases for the legs or arms in either training group (p 0.05). The data from this study suggest that multiple sets produce greater increases in percentage strength gains for simple exercises in untrained adults. It is possible that neural mechanisms are responsible for the observed differences.