Whey protein but not collagen peptides stimulate acute and longer-term muscle protein synthesis with and without resistance exercise in healthy older women: a randomized controlled trial

Abstract

ABSTRACT Background Aging appears to attenuate the response of skeletal muscle protein synthesis (MPS) to anabolic stimuli such as protein ingestion (and the ensuing hyperaminoacidemia) and resistance exercise (RE). Objectives The purpose of this study was to determine the effects of protein quality on feeding- and feeding plus RE–induced increases of acute and longer-term MPS after ingestion of whey protein (WP) and collagen protein (CP). Methods In a double-blind parallel-group design, 22 healthy older women (mean ± SD age: 69 ± 3 y, n = 11/group) were randomly assigned to consume a 30-g supplement of either WP or CP twice daily for 6 d. Participants performed unilateral RE twice during the 6-d period to determine the acute (via [13C6]-phenylalanine infusion) and longer-term (ingestion of deuterated water) MPS responses, the primary outcome measures. Results Acutely, WP increased MPS by a mean ± SD 0.017 ± 0.008%/h in the feeding-only leg (Rest) and 0.032 ± 0.012%/h in the feeding plus exercise leg (Exercise) (both P < 0.01), whereas CP increased MPS only in Exercise (0.012 ± 0.013%/h) (P < 0.01) and MPS was greater in WP than CP in both the Rest and Exercise legs (P = 0.02). Longer-term MPS increased by 0.063 ± 0.059%/d in Rest and 0.173 ± 0.104%/d in Exercise (P < 0.0001) with WP; however, MPS was not significantly elevated above baseline in Rest (0.011 ± 0.042%/d) or Exercise (0.020 ± 0.034%/d) with CP. Longer-term MPS was greater in WP than in CP in both Rest and Exercise (P < 0.001). Conclusions Supplementation with WP elicited greater increases in both acute and longer-term MPS than CP supplementation, which is suggestive that WP is a more effective supplement to support skeletal muscle retention in older women than CP. This trial was registered at clinicaltrials.gov as NCT03281434.