Effects of leucine-enriched essential amino acid and whey protein bolus dosing upon skeletal muscle protein synthesis at rest and after exercise in older women

Wilkinson, Daniel J.; Bukhari, Syed S.I.; Phillips, Bethan E.; Limb, Marie C.; Cegielski, Jessica; Brook, Matthew S.; Rankin, Debbie; Mitchell, William K.; Kobayashi, Hisamine; Lund, Jonathan; Williams, John P.; Greenhaff, Paul L.; Smith, Kenneth; Atherton, Philip J.

Abstract

© 2017 The Authors Background & aims: Impaired anabolic responses to nutrition and exercise contribute to loss of skeletal muscle mass with ageing (sarcopenia). Here, we tested responses of muscle protein synthesis (MPS), in the under represented group of older women, to leucine-enriched essential amino acids (EAA) in comparison to a large bolus of whey protein (WP). Methods: Twenty-four older women (65 ± 1 y) received (N = 8/group) 1.5 g leucine-enriched EAA supplements (LEAA_1.5), 6 g LEAA (LEAA_6) in comparison to 40 g WP. A primed constant I.V infusion of 13 C 6 -phenylalanine was used to determine MPS at baseline and in response to feeding (FED) and feeding-plus-exercise (FED-EX; 6 × 8 unilateral leg extensions; 75%1-RM). We quantified plasma insulin/AA concentrations, leg femoral blood flow (LBF)/muscle microvascular blood flow (MBF), and anabolic signalling via immunoblotting. Results: Plasma insulineamia and EAAemia were greater and more prolonged with WP than LEAA, although LEAA_6 peaked at similar levels to WP. Neither LEAA or WP modified LBF or MBF. FED increased MPS similarly in the LEAA_1.5, LEAA_6 and WP (P < 0.05) groups over 0–2 h, with MPS significantly higher than basal in the LEAA_6 and WP groups only over 0–4 h. However, FED-EX increased MPS similarly across all the groups from 0 to 4 h (P < 0.05). Only p-p70S6K1 increased with WP at 2 h in FED (P < 0.05), and at 2/4 h in FED-EX (P < 0.05). Conclusions: In conclusion, LEAA_1.5, despite only providing 0.6 g of leucine, robustly (perhaps maximally) stimulated MPS, with negligible trophic advantage of greater doses of LEAA or even to 40 g WP. Highlighting that composition of EAA, in particular the presence of leucine rather than amount is most crucial for anabolism.

Citation

Wilkinson, D. J., Bukhari, S. S., Phillips, B. E., Limb, M. C., Cegielski, J., Brook, M. S., Rankin, D., Mitchell, W. K., Kobayashi, H., Lund, J., Williams, J. P., Greenhaff, P. L., Smith, K., & Atherton, P. J. (2018). Effects of leucine-enriched essential amino acid and whey protein bolus dosing upon skeletal muscle protein synthesis at rest and after exercise in older women. Clinical Nutrition, 37(6), 2011-2021. https://doi.org/10.1016/j.clnu.2017.09.008

• Journal Article Type: Article
• Acceptance Date: Sep 19, 2017
• Online Publication Date: Sep 23, 2017
• Publication Date: Dec 1, 2018
• Deposit Date: Nov 7, 2017
• Publicly Available Date: Nov 7, 2017
• Journal: Clinical Nutrition
• Print ISSN: 0261-5614
• Electronic ISSN: 1532-1983
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 37
• Issue: 6
• Pages: 2011-2021
• DOI: https://doi.org/10.1016/j.clnu.2017.09.008
• Keywords: Muscle protein synthesis; Leucine; Ageing; Low dose amino acid supplementation; Exercise; Human metabolism
• Public URL: https://nottingham-repository.worktribe.com/output/883934
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0261561417313407
• Additional Information: This article is maintained by: Elsevier; Article Title: Effects of leucine-enriched essential amino acid and whey protein bolus dosing upon skeletal muscle protein synthesis at rest and after exercise in older women; Journal Title: Clinical Nutrition; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.clnu.2017.09.008; Content Type: article; Copyright: © 2017 The Authors. Published by Elsevier Ltd.
• Contract Date: Nov 7, 2017