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
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…
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 16 participants or records.
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