A randomized controlled trial of the impact of protein supplementation on leg lean mass and integrated muscle protein synthesis during inactivity and energy restriction in older persons
The American Journal of Clinical Nutrition, Volume 108, Issue 5, November 2018, Pages 1060–1068, https://doi.org/10.1093/ajcn/nqy193
ABSTRACT
Background
In older persons, muscle loss is accelerated during physical inactivity and hypoenergetic states, both of which are features of hospitalization. Protein supplementation may represent a strategy to offset the loss of muscle during inactivity, and enhance recovery on resumption of activity.
Objective
We aimed to determine if protein supplementation, with proteins of substantially different quality, would alleviate the loss of lean mass by augmenting muscle protein synthesis (MPS) while inactive during a hypoenergetic state.
Design
Participants (16 men, mean ± SD age: 69 ± 3 y; 15 women, mean ± SD age: 68 ± 4 y) consumed a diet containing 1.6 g protein · kg–1 · d–1, with 55% ± 9% of protein from foods and 45% ± 9% from supplements, namely, whey protein (WP) or collagen peptides (CP): 30 g each, consumed 2 times/d. Participants were in energy balance (EB) for 1 wk, then began a period of energy restriction (ER; –500 kcal/d) for 1 wk, followed by ER with step reduction (ER + SR; <750 steps/d) for 2 wk, before a return to habitual activity in recovery (RC) for 1 wk.
Results
There were significant reductions in leg lean mass (LLM) from EB to ER, and from ER to ER + SR in both groups (P < 0.001) with no differences between WP and CP or when comparing the change from phase to phase. During RC, LLM increased from ER + SR, but in the WP group only. Rates of integrated muscle protein synthesis decreased during ER and ER + SR in both groups (P < 0.01), but increased during RC only in the WP group (P = 0.05).
Conclusions
Protein supplementation did not confer a benefit in protecting LLM, but only supplemental WP augmented LLM and muscle protein synthesis during recovery from inactivity and a hypoenergetic state. This trial was registered at http://www.clinicaltrials.gov as NCT03285737.
病床で安静状態を保っている間は、タンパク質を多めに摂取しても、骨格筋の減少を抑えるのは難しい。そうではないかと薄々は思っていたが、改めてデータを示されると、ちょっと悲しい気持ちになる。
但し、回復・リハビリ期では、有意差アリ。ここで(無理をしない程度に)頑張って、筋力を取り戻してもらおう。
