Resistance Training in Healthy Older Adults — Do We Need to Supplement Dietary Protein?
By Lex B. Verdijk, Ph.D. and Luc J.C. van Loon, Ph.D.
Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM.
Dr. Verdijk is a researcher and Assistant Professor at the Department of Human Movement Sciences at Maastricht University Medical Centre+, the Netherlands. His research focuses on the role of exercise and nutrition in the regulation of skeletal muscle mass and function, with special interest in the aging human.
Dr. van Loon is a Professor of Physiology of Exercise at the Department of Human Movement Sciences, Maastricht University Medical Centre+, the Netherlands. An ACSM member, Dr. van Loon leads the M3 Research Unit at Maastricht University. The main fields of investigation in his research unit include human skeletal muscle metabolism, exercise metabolism, sports nutrition, adaptation to endurance and resistance type exercise training, and the use of combined physical activity and/or dietary (lifestyle) interventions to improve health and/or functional performance in chronic metabolic disease (obesity and type 2 diabetes) and aging.
This commentary presents Dr. Verdijk’s and Dr. van Loon’s views on the topic of a research article which they and their colleagues published in the March 2013 issue of Medicine and Science in Sports and Exercise®, “Protein supplementation during resistance-type exercise training in the elderly”.
Muscle mass, strength, and function progressively decline with increasing age. This process has been termed “sarcopenia”, and ultimately results in physical disability, loss of independence, and reduced quality of life. Since both decreased physical activity and inadequate food intake play a key role in the development of sarcopenia, exercise and/or nutritional interventions are considered important tools in its treatment. Resistance type exercise training is currently regarded as the most effective intervention strategy to counteract loss of muscle mass and function with aging. Although several studies have suggested that protein supplementation may be of additional benefit, there is no clear evidence that older adults should combine resistance training with protein supplementation to optimize the effects of exercise. Inconclusive findings are likely caused by differences in the populations studied, the amount, type, and timing of supplements, and duration of the intervention programs.
In our recent MSSE paper, we describe a long-term intervention study in which 60 healthy elderly men and women (~70 years) performed 6 months of progressive, whole-body resistance type exercise training (3x/wk), either with or without additional protein supplementation. The supplementation consisted of a milk-based protein drink, providing 15 g additional protein per day, or a non-protein placebo drink. Drinks were taken at breakfast, since we previously showed that protein intake is particularly low with this meal. Six months of resistance training effectively increased muscle mass, strength, and functional performance at the whole-body, whole-muscle, and muscle fiber level in both the men and women. In addition, significant improvements in glucose homeostasis, blood lipid profile, and blood pressure were shown. However, improvements in muscle mass, strength, function and metabolic risk factors were similar for the protein- and the placebo-supplemented groups, showing no additional benefits of protein supplementation.
Interestingly, in a recent meta-analysis that included data on 680 subjects, we report that protein supplementation does augment muscle mass and strength gains in response to resistance type exercise training in both the young and old. Compared with the effects of exercise training however, the surplus benefits of protein supplementation are relatively small. Such small differences in net muscle gain are hard to detect in a single nutritional intervention study. Clearly though, both exercise training and a healthy diet (providing sufficient protein) are of key importance in the maintenance of skeletal muscle mass and function with aging. The effects of nutritional (co)intervention may be maximized by using the optimal amount and type of dietary protein and the optimal timing of supplementation. Future work should be directed towards defining the optimal strategy of combining resistance type exercise training with nutritional support to attenuate and/or reverse sarcopenia and, as such, support healthy aging.
