Journal article
A protein–leucine supplement increases branched-chain amino acid and nitrogen turnover but not performance
Medicine & Science in Sports & Exercise, Vol.44(1), pp.57-68
2012
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Abstract
<p><p id="x-x-x-x-P14">Purpose: This study aimed to determine the effect of postexercise protein–leucine coingestion with CHO–lipid on subsequent high-intensity endurance performance and to investigate candidate mechanisms using stable isotope methods and metabolomics. <p id="x-x-x-x-P15">Methods: In this double-blind, randomized, crossover study, 12 male cyclists ingested a leucine/protein/CHO/fat supplement (LEUPRO 7.5/20/89/22 g·h<sup>−1</sup>, respectively) or isocaloric CHO/fat control (119/22 g·h<sup>−1</sup>) 1–3 h after exercise during a 6-d training block (intense intervals, recovery, repeated-sprint performance rides). Daily protein intake was clamped at 1.9 g·kg<sup>−1</sup>·d<sup>−1</sup> (LEUPRO) and 1.5 g·kg<sup>−1</sup>·d<sup>−1</sup> (control). Stable isotope infusions (1-<sup>13</sup>C-leucine and 6,6-<sup>2</sup>H<sub>2</sub>-glucose), mass spectrometry–based metabolomics, and nitrogen balance methods were used to determine the effects of LEUPRO on whole-body branched-chain amino acid (BCAA) and glucose metabolism and protein turnover. <p id="x-x-x-x-P16">Results: After exercise, LEUPRO increased BCAA levels in plasma (2.6-fold; 90% confidence limits = ×/÷1.1) and urine (2.8-fold; ×/÷1.2) and increased products of BCAA metabolism plasma acylcarnitine C5 (3.0-fold; ×/÷0.9) and urinary leucine (3.6-fold; ×/÷1.3) and β-aminoisobutyrate (3.4-fold; ×/÷1.4), indicating that ingesting ∼10 g leucine per hour during recovery exceeds the capacity to metabolize BCAA. Furthermore, LEUPRO increased leucine oxidation (5.6-fold; ×/÷1.1) and nonoxidative disposal (4.8-fold; ×/÷1.1) and left leucine balance positive relative to control. With the exception of day 1 (LEUPRO = 17 ± 20 mg N·kg<sup>−1</sup>, control = −90 ± 44 mg N·kg<sup>−1</sup>), subsequent (days 2–5) nitrogen balance was positive for both conditions (LEUPRO = 130 ± 110 mg N·kg<sup>−1</sup>, control = 111 ± 86 mg N·kg<sup>−1</sup>). Compared with control feeding, LEUPRO lowered the serum creatine kinase concentration by 21%–25% (90% confidence limits = ±14%), but the effect on sprint power was trivial (day 4 = 0.4% ± 1.0%, day 6 = −0.3% ± 1.0%). <p id="x-x-x-x-P17">Conclusions: Postexercise protein–leucine supplementation saturates BCAA metabolism and attenuates tissue damage, but effects on subsequent intense endurance performance may be inconsequential under conditions of positive daily nitrogen balance.</p>
Details
- Title
- A protein–leucine supplement increases branched-chain amino acid and nitrogen turnover but not performance
- Creators
- Andre R Nelson - Massey UniversityStuart M Phillips - McMaster UniversityTrent Stellingwerff - Nestle Research CentreSerge Rezzi - Nestle Research CentreStephen J Bruce - Nestle Research CentreIsabelle Breton - Nestle Research CentreAnita Thorimbert - Nestle Research CentrePhilippe A Guy - Nestle Research CentreJim Clarke - Massey UniversitySuzanne Broadbent - Southern Cross UniversityDavid Stephen Rowlands
- Publication Details
- Medicine & Science in Sports & Exercise, Vol.44(1), pp.57-68
- Identifiers
- 2453; 991012820695802368
- Academic Unit
- School of Health and Human Sciences
- Resource Type
- Journal article