Daniel J. Wilkinson
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.
Syed S.I. Bukhari Syed.Bukhari@nottingham.ac.uk
Bethan E. Phillips
Marie C. Limb
Matthew S. Brook
William K. Mitchell
John P. Williams
Jonathan N. Lund
Paul L. Greenhaff firstname.lastname@example.org
Philip J. Atherton
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|
|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|
|Keywords||Muscle protein synthesis; Leucine; Ageing; Low dose amino acid supplementation; Exercise; Human metabolism|
|Copyright Statement||Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0|
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0
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