|Cloutier, Gregory J.|
|Phillips, Edward M.|
|Fielding, Roger A.|
Submitted to: Journals of Gerontology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2012
Publication Date: 6/1/2013
Citation: Chale, A., Cloutier, G., Hau, C., Phillips, E., Dallal, G., Fielding, R. 2013. Efficacy of whey protein supplementation on resistance exercise-induced changes in muscle strength, lean mass, and function in mobility-limited older adults. Journals of Gerontology. 68(6):682-690. Interpretive Summary: Aging is associated with a loss of muscle mass, resulting in strength and functional decline. It is well known that proper nutrition and regular exercise can help slow this age-related muscle loss. Whey is a source of protein found in dairy products. It contains abundant essential amino acids, which are crucial for muscle growth and recovery. Whey protein supplementation combined with resistance training has shown to be effective in stimulating muscle growth among healthy young adults, but the effect among older adults has not yet been confirmed. Therefore, the present study was conducted to determine changes in muscle quality and physical function with whey protein supplementation in frail older adults. The results showed that both whey protein and control supplementation groups had improvement in muscle size, muscle strength, and functional capacity after 6 months of resistance training. However, no significant difference was found between groups. This negative response might be due to reduction in caloric intake. Hence, future investigation is needed to substantiate the current findings.
Technical Abstract: Whey protein supplementation may augment resistance exercise-induced increases in muscle strength and mass. Further studies are required to determine whether this effect extends to functionally compromised older adults. The objectives of the study were to compare the effects of whey protein concentrate (WPC) supplementation to an isocaloric control on changes in muscle strength, whole body lean mass, mid-thigh muscle cross sectional area (CSA), and stair-climbing performance in older mobility-limited adults in response to 6 months of resistance training (RT). Eighty mobility-limited adults aged 70-85 y were randomized to receive WPC (40 g/day) or an isocaloric control (maltodextrin) for 6 months. All subjects also completed a progressive RT intervention (3 x per wk; 5 exercises; 10 to 12 repetitions; 80% one repetition maximum [1-RM]). Supplement adherence was 72.1 + 29.3% and 82.3 + 21.9% and exercise adherence was 79.9 + 20.8% and 80.2 + 21.7% in the WPC and control groups, respectively. Muscle strength increased 16-50% in WPC and control groups; muscle CSA and lean mass were increased 4.6% and 1.7%, and 1.3% and 0.6% in the WPC and control groups, respectively. Stair climbing performance also improved in both groups. However, there were no statistically significant differences in the change in any of these variables between the WPC and control groups. These data suggest that WPC supplementation at this dose does not offer additional benefit to the effects of high intensity RT in functionally limited older adults.