[Objective] The aim of this study was to evaluate the effects of increased dietary protein in elderly participants during strength training.
[Methods] This study was a randomized controlled clinical trial. Twenty-three participants (average age of 69.1 years) were recruited to perform a 3-month twice per week strength-training program with or without an intervention to increase protein intake. The 23 participants were randomly distributed into a strength training only group (n=12) or a strength training combined with nutritional intervention group (n=11). Three registered dietitians educated the nutritional intervention group once every 3 weeks to facilitate increased intake of protein-rich foods( e.g., meat, fish, soybeans, and dairy products).
[Results] Protein intake of the nutrition intervention group significantly increased to 18.3 g/day during the 3-month study period. However, no significant difference was observed for energy, carbohydrate, and lipid intake levels between the strength-training only group and the nutritional intervention group. Our principal analysis revealed 4 component patterns and component-1 was labeled as exercise capacity. This component score significantly increased during the strength training period in both groups; however, analysis of covariance (parallelism test) revealed that both groups had an identical correlation coefficient (p=0.975).
[Discussion] In contrast to protein intake studies focused on supplements, increased intake of protein-rich foods did not increase the efficacy of strength training in the study participants. This outcome may result from age associated dysfunctional intestinal absorptive capacity and/or mastication power for proteins.
