Journal
AMERICAN JOURNAL OF CLINICAL NUTRITION
Volume 113, Issue 4, Pages 790-800Publisher
OXFORD UNIV PRESS
DOI: 10.1093/ajcn/nqaa372
Keywords
protein supplementation; ageing; skeletal muscle; resistance training; randomized controlled trials; exercise
Categories
Funding
- University of Copenhagen Excellence Program for Interdisciplinary Research
- Danish Dairy Research Foundation
- P. Carl Petersen Fund
- Region H Research Fund
- Arla Foods Ingredients P/S
- Innovation Foundation Denmark
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Protein supplementation alone was found to be ineffective in improving muscle mass and strength in healthy older adults, while heavy-resistance training combined with whey protein supplementation proved to be the most effective intervention for preserving muscle mass and increasing strength. Additional strategies to improve long-term compliance to heavy resistance exercise in this population are recommended for future studies.
Background: Protein supplementation alone or combined with resistance training has been proposed to be effective in counteracting age-related losses of muscle mass and strength. Objectives: To investigate the effect of protein supplementation alone or combined with light-intensity or heavy-load resistance exercise on muscle size, strength, and function in older adults. Methods: In a 1-y randomized controlled trial, 208 healthy older adults (>65 y) were randomly assigned to 1 of 5 interventions: 1) carbohydrate supplementation (CARB); 2) collagen protein supplementation (COLL); 3) whey protein supplementation (WHEY); 4) light-intensity resistance training 3-5 times/wk with whey protein supplementation (LITW); and 5) heavy resistance training 3 times weekly with whey protein supplementation (HRTW). Protein supplements contained 20 g protein + 10 g carbohydrate, whereas CARB contained 30 g of carbohydrates. All intervention groups received the supplement twice daily. The primary outcome was change in the quadriceps cross-sectional area (qCSA). Secondary outcomes included measures of lower extremity strength and power, functional capabilities, and body composition. Results: There were 184 participants who completed the study. COLL andWHEY did not affect any measured parameter compared to CARB. Compared to WHEY, HRTW improved the qCSA size (between-group difference, +1.68 cm(2); 95% CI, +0.41 to +2.95 cm(2); P = 0.03), as well as dynamic (+18.4 Nm; 95% CI, +10.1 to +26.6 Nm; P < 10(-4)) and isometric knee extensor strength (+23.9 Nm; 95% CI, +14.2 to +33.6 Nm; P < 10(-5)). LITW did not improve the qCSA size, but increased dynamic knee extensor strength compared to WHEY (+13.7 Nm; 95% CI, +5.3 and +22.1 Nm; P = 0.01). Conclusions: Recommending protein supplementation as a stand-alone intervention for healthy older individuals seems ineffective in improving muscle mass and strength. Only HRTW was effective in both preserving muscle mass and increasing strength. Thus, we recommend that future studies investigate strategies to increase long-term compliance to heavy resistance exercise in healthy older adults.
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