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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; Williams, John P.; Lund, Jonathan N.; Greenhaff, Paul L.; Smith, Kenneth; Atherton, Philip J.

Authors

Daniel J. Wilkinson

Syed S.I. Bukhari Syed.Bukhari@nottingham.ac.uk

Bethan E. Phillips

Marie C. Limb

Jessica Cegielski

Matthew S. Brook

Debbie Rankin

William K. Mitchell

Hisamine Kobayashi

John P. Williams

Jonathan N. Lund

Paul L. Greenhaff paul.greenhaff@nottingham.ac.uk

Kenneth Smith

Philip J. Atherton



Abstract

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 ¼ 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 13C6-phenylalanine was used to determine MPS at baseline and in response to feeding (FED) and feeding-plus-exercise (FED-EX; 6 x 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 0e2 h, with MPS significantly higher than basal in the LEAA_6 and WP groups only over 0e4 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.

Journal Article Type Article
Publication Date Sep 23, 2017
Journal Clinical Nutrition
Print ISSN 0261-5614
Electronic ISSN 1532-1983
Publisher Elsevier
Peer Reviewed Peer Reviewed
APA6 Citation Wilkinson, D. J., Bukhari, S. S., Phillips, B. E., Limb, M. C., Cegielski, J., Brook, M. S., …Atherton, P. J. (2017). 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, doi:10.1016/j.clnu.2017.09.008. ISSN 0261-5614
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
Publisher URL https://www.sciencedirect.com/science/article/pii/S0261561417313407
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0
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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0





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