Date of Graduation


Document Type


Degree Name

Doctor of Philosophy in Kinesiology (PhD)

Degree Level



Health, Human Performance and Recreation


Michelle Gray

Committee Member

Nicholas Greene

Second Committee Member

Ro Dibrezzo

Third Committee Member

Tyrone Washington

Fourth Committee Member

Ronna Turner


Aging, Autoregulatory Progressive Resistance Exercise, Exercise Science, Protein, Resistance Training, Sports/Nutrition Supplementation


PURPOSE: The purpose of this study was to investigate the effects of 12 weeks of protein supplementation and Autoregulatory Progressive Resistance Exercise (APRE) training on measures of body composition, muscular performance, and free testosterone in middle-aged men. METHODS: Untrained males (n = 35; 43.3 ± 6.6 years) participated in this study. Lean mass (LM) and fat mass (FM) were measured via Dual Energy X-ray Absorptiometry (DEXA), while strength was measured utilizing one repetition maximum (1RM), endurance measured using maximum repetitions completed (REPS) at 75% 1RM for the bench and leg press, and free testosterone was measured using changes in serum values. Subjects were randomly placed into one of four groups: protein (PO), APRE, protein plus APRE (PAPRE), or control (CON). Subjects repeated testing for the DEXA, 1RM, REPS, and blood draw every four weeks for 12 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 12 weeks. RESULTS: Analysis revealed a significant time interaction (p < .01) and a trend towards significance for group time interaction (p = .08) between baseline and week 12 for LM, with the APRE and PAPRE groups showing a significant increase following the 12-weeks. Significant time and group by time interactions (p < .01) occurred for BP and LP 1RM. APRE and PAPRE displayed increases at multiple times over the course of the 12-weeks for both BP and LP, while the PRO and CON groups exhibited increases for LP only. While REPS remained unchanged (p > .05), volume lifted exhibited a significant time interaction between baseline and week 12 for BP and LP (p < .01), and a significant group by time interaction for LP (p < .01). PRO increased BP volume, and PAPRE increased both BP and LP volume, while APRE and CON remained relatively the same following the 12-weeks. There were no significant changes in serum free testosterone over the course of the 12-week study. CONCLUSION: APRE, alone and in combination with supplemental protein, provides greater benefits in changes in LM and muscular performance compared to that of supplemental protein alone for middle-aged men following a 12-week intervention.