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

Am J Clin Nutr. 2018 Nov 1;108(5):1060-1068. doi: 10.1093/ajcn/nqy193.


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.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Caloric Restriction
  • Collagen / pharmacology
  • Convalescence
  • Dietary Supplements*
  • Energy Intake*
  • Energy Metabolism
  • Female
  • Hospitalization
  • Humans
  • Leg
  • Male
  • Motor Activity*
  • Muscle Proteins / biosynthesis*
  • Muscle, Skeletal / drug effects*
  • Muscle, Skeletal / metabolism
  • Peptides / pharmacology
  • Protein Biosynthesis / drug effects*
  • Rest
  • Walking
  • Whey Proteins / pharmacology*


  • Muscle Proteins
  • Peptides
  • Whey Proteins
  • Collagen

Associated data

  • ClinicalTrials.gov/NCT03285737