The Interactive Effects of Beta-Alanine and Resistance Training on Muscular Endurance in Older Adults

of a dissertation at the University of Miami. Muscular endurance is a major neuromuscular factor affecting independence and fall probability in older persons. PURPOSE: To determine the effects of sustained-release beta-alanine supplementation alone or in combination with a resistance training program on muscular and daily activity-based performances in older adults. METHODS: Twenty-seven subjects, 60-82 years of age, were randomly assigned to one of four groups for a 12-week intervention: 3.2g/day placebo without resistance training, 3.2g/day beta-alanine without resistance training, 3.2g/day placebo with resistance training, or 3.2g/day beta-alanine with resistance training. Before and after the intervention, subjects' anthropometric, Physical Functional Performance 10, Senior Fitness and upper and lower body strength and endurance assessments were performed. Upper and lower body strength and endurance tests included one-repetition maximum (1RM) and 20 repetitions power tests at 50% 1RM using pneumatic resistance equipment. RESULTS: Twenty-seven subjects completed post-testing. Beta-alanine was well tolerated with only 1 subject reporting any side effect (muscular aches). Multiple 4 (group) x 2 (time) mixed design ANOVA's indicated no significant group x time interactions (p > .05) for any anthropometric or performance measures except 1RM leg press (p = .010). A post-hoc analysis revealed significant improvements in 1RM leg press for both the resistance training groups (p < .001); while no significant between group difference was detected. For the 20-repetition chest and leg press tests, no differences were detected for time, group or time x group interactions (p < .001). When untrained and trained groups were compared, significant effects of time (p < .001) and repetition (p < .001), and significant repetition x training status (p < .01) and time x repetition by training status interactions (p = .019) were detected. Pairwise t-tests with Bonferroni adjustment (p < .0025) for both tests revealed only one difference between pretest and post-test across repetitions for the untrained group; while the training group showed significant increases across time for multiple repetitions. When comparing pretest and post-test power patterns across repetitions for chest press, there were nearly linear declines with a lack of significant differences between pretest and post-test for the untrained group. In contrast, the trained group showed a more rapid decline in power across repetitions during pretest than during post-test. For the untrained group during leg press, no significant differences were detected across repetitions for pretest or post-test; however, the trained group presented a pattern of gradual increases in power and changes in …