Body Composition And Muscular Performance Following 8-weeks Of Resistance-training And Protein Supplementation

Abstract

Increased protein intake in the diet decreases fat mass (FM) and increases lean mass (LM). Resistance training increases LM, as well as increases muscular strength. Together, protein supplementation and resistance exercise work synergistically when taken prior to or following exercise. PURPOSE: The purpose of this pilot study was to investigate the effects 8 weeks of protein supplementation and Autoregulatory Progressive Resistance Exercise (APRE) training had on measures of body composition and muscular performance. METHODS: Untrained males (n = 22; 42.1 ± 7.1 years) participated in this pilot study. LM and FM were measured via Dual Energy X-ray Absorptiometry (DEXA), while strength was measured utilizing one repetition maximum (1RM), and endurance measured using maximum repetitions completed (REPS) at 75% 1RM for the bench and leg press. Subjects were randomly placed into one of four groups: control (CON), protein (PO), APRE, or protein plus APRE (PAPRE). Subjects repeated testing for the DEXA, 1RM, and REPS every four weeks for 8 weeks. Both PO and PAPRE groups ingested 25g of supplemental protein twice daily. Subjects in the exercise groups completed a resistance training program, 3 days per week, for 8 weeks, or 24 training sessions. RESULTS: Repeated measures ANOVA indicated a significant group by time interaction for LM, bench press 1RM, and leg press 1RM (p < .05). LM increased by 4% (+2.3 ± 0.2kg) in the PAPRE group, while increases in bench and leg press 1RM were 23% (+14.7 ± 0.7kg) and 50% (+132.1 ± 13.9 kg), respectively. There were no other group by time interactions for any of the variables assessed (p > .05). LM (p < .05), bench press 1RM (p < .001), and leg press 1RM (p < .001) indicated a significant time effect (+0.93 ± 0.02kg, +6.3 ± 0.9kg, and +68.2 ± 2.5kg, respectively). Body fat percentage showed a trend for decreasing over time (p = .05), while FM was significantly reduced over the 8-week training period (p < .05). Bench press increased 20% (+13.0 ± 2.0kg) from baseline for the APRE group, while leg press increased 13% (+32.9 ± 7.3kg), 18% (+43.1 ± 8.5kg), and 20% (+64.6 ± 28.8kg) for CON, PO, and APRE groups, respectively. CONCLUSION: The synergistic effects of protein plus exercise can be seen with the PAPRE group out-performing all other groups given the significant increases in LM and muscular strength over 8 weeks.