According to recent research published in the American Journal of Clinical Nutrition, investigators have seen that recommending protein supplementation as a stand-alone intervention for healthy older individuals seems ineffective in improving muscle mass and strength.
Protein supplementation alone or combined with resistance training has been proposed to be effective in counteracting age-related losses of muscle mass and strength.
Therefore, Kenneth H Mertz and colleagues from the Institute of Sports Medicine, Department of Orthopaedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark recently conducted this study on a total of 184 participants 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.
The authors carried out a 1-y randomized controlled trial in which 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.
The results of the study showed that-
a. COLL and WHEY did not affect any measured parameter compared to CARB.
b. Compared to WHEY, HRTW improved the qCSA size (between-group difference, +1.68 cm2; 95% CI, +0.41 to +2.95 cm2; 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).
c. 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).
Therefore, the authors concluded that "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, the researchers recommended that future studies are needed to investigate strategies to increase long-term compliance to heavy resistance exercise in healthy older adults.