Med Sci Sports Exerc. 2011 Jun 16. [Epub ahead of print]
A Protein-Leucine Supplement Increases BCAA and Nitrogen Turnover but not Performance.
Nelson AR, Phillips SM, Stellingwerff T, Rezzi S, Bruce SJ, Breton I, Thorimbert A, Guy PA, Clarke J, Broadbent S, Rowlands DS. Source
11School of Sport and Exercise, Massey University, Wellington, New Zealand; 2Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada; 3Nestle Research Center, Lausanne, Switzerland; 4School of Sport and Exercise Science, Victoria University, Melbourne, Victoria, Australia. Abstract PURPOSE:
To determine the effect of post-exercise protein-leucine co-ingestion with carbohydrate-lipid on subsequent high-intensity endurance performance, and to investigate candidate mechanisms using stable isotope methods and metabolomics. METHODS:
In a double-blind randomized crossover, 12 male cyclists ingested a leucine/protein/carbohydrate/fat supplement (LEUPRO, respectively 7.5/20/89/22 g·h) or isocaloric carbohydrate/fat control (119/22 g·h) 1-3 h post-exercise during a 6-day training block (intense intervals, recovery, repeated-sprint performance rides). Daily protein intake was clamped at 1.9 (LEUPRO) and 1.5 g·kg·d (control). Stable isotope infusions (1-C-leucine and 6,6-H2-glucose), mass-spectrometry based metabolomics, and nitrogen balance methodology were used to determine effects of LEUPRO on whole-body branch-chain amino acid (BCAA) and glucose metabolism, and protein turnover. RESULTS:
Following exercise, LEUPRO increased BCAAs in plasma (2.6-fold; 90%CL ×/÷1.1) and urine (2.8-fold; ×/÷1.2), and 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 ingesting ∼10 g·leucine·h-1 during recovery exceeds the capacity to metabolise BCAA. Furthermore, LEUPRO increased leucine oxidation (5.6-fold; ×/÷1.1), non-oxidative 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; control -90 ± 44 mg N·kg), subsequent (day 2-5) nitrogen balance was positive for both conditions (LEUPRO 130 ± 110 mg N·kg; control 111 ± 86 mg N·kg). Compared to control feeding, LEUPRO lowered the serum creatine kinase concentration by 21-25% (90%CL ±14%), but the impact on sprint power was trivial (day 4: 0.4% ±1.0%; day 6: -0.3% ±1.0%). CONCLUSION:
Post-exercise leucine-protein 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.