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h2s
11-12-2012, 11:31 AM
Branched-chain amino acid supplementation increases the lactate threshold during an incremental exercise test in trained individuals.


Branched-chain amino acid supplementation increases the lactate threshold during an incremental exercise test in trained individuals.
Matsumoto K, Koba T, Hamada K, Tsujimoto H, Mitsuzono R.
Source

Saga Nutraceuticals Research Institute, Otsuka Pharmaceutical Co., Ltd., Yoshinogari, Kanzaki, Saga 842-0195, Japan.
Abstract

The effects of branched-chain amino acid (BCAA) supplementation on the lactate threshold (LT) were investigated as an index of endurance exercise capacity. Eight trained male subjects (21+/-2 y) participated in a double-blind crossover placebo-controlled study. The subjects were randomly assigned to two groups and were provided either a BCAA drink (0.4% BCAA, 4% carbohydrate; 1,500 mL/d) or an iso-caloric placebo drink for 6 d. On the 7th day, the subjects performed an incremental loading exercise test with a cycle ergometer until exhaustion in order to measure the LT. The test drink (500 mL) was ingested 15-min before the test. Oxygen consumption VO2 and the respiratory exchange ratio (RER) during the exercise test were measured with the breath-by-breath method. Blood samples were taken before and during the exercise test to measure the blood lactate and plasma BCAA concentrations. The same exercise test was performed again 1 wk later. BCAA supplementation increased the plasma BCAA concentration during the exercise test, while plasma BCAA concentration decreased in the placebo trial. The RER during the exercise test in the BCAA trial was lower than that in the placebo trial (p<0.05). The VO2 and workload levels at LT point in the BCAA trial were higher than those in the placebo trial (VO2: 29.8+/-6.8 vs. 26.4+/-5.4 mL/kg/min; workload: 175+/-42 vs. 165+/-38 W, p<0.05, respectively). The VO2max in the BCAA trial was higher than that in the placebo trial (47.1+/-5.7 vs. 45.2+/-5.0 mL/kg/min, p<0.05). These results suggest that BCAA supplementation may be effective to increase the endurance exercise capacity.

Branched-chain amino acid suppl... [J Nutr Sci Vitaminol (Tokyo). 2009] - PubMed - NCBI (http://www.ncbi.nlm.nih.gov/pubmed/19352063)

h2s
11-12-2012, 11:36 AM
Intake of branched-chain amino acids influences the levels of MAFbx mRNA and MuRF-1 total protein in resting and exercising human muscle.


Intake of branched-chain amino acids influences the levels of MAFbx mRNA and MuRF-1 total protein in resting and exercising human muscle.
Borgenvik M, Aprˇ W, Blomstrand E.
Source

The ┼strand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden.
Abstract

Resistance exercise and amino acids are two major factors that influence muscle protein turnover. Here, we examined the effects of resistance exercise and branched-chain amino acids (BCAA), individually and in combination, on the expression of anabolic and catabolic genes in human skeletal muscle. Seven subjects performed two sessions of unilateral leg press exercise with randomized supplementation with BCAA or flavored water. Biopsies were collected from the vastus lateralis muscle of both the resting and exercising legs before and repeatedly after exercise to determine levels of mRNA, protein phosphorylation, and amino acid concentrations. Intake of BCAA reduced (P < 0.05) MAFbx mRNA by 30 and 50% in the resting and exercising legs, respectively. The level of MuRF-1 mRNA was elevated (P < 0.05) in the exercising leg two- and threefold under the placebo and BCAA conditions, respectively, whereas MuRF-1 total protein increased by 20% (P < 0.05) only in the placebo condition. Phosphorylation of p70(S6k) increased to a larger extent (∼2-fold; P < 0.05) in the early recovery period with BCAA supplementation, whereas the expression of genes regulating mTOR activity was not influenced by BCAA. Muscle levels of phenylalanine and tyrosine were reduced (13-17%) throughout recovery (P < 0.05) in the placebo condition and to a greater extent (32-43%; P < 0.05) following BCAA supplementation in both resting and exercising muscle. In conclusion, BCAA ingestion reduced MAFbx mRNA and prevented the exercise-induced increase in MuRF-1 total protein in both resting and exercising leg. Further-more, resistance exercise differently influenced MAFbx and MuRF-1 mRNA expression, suggesting both common and divergent regulation of these two ubiquitin ligases.

Intake of branched-chain amino... [Am J Physiol Endocrinol Metab. 2012] - PubMed - NCBI (http://www.ncbi.nlm.nih.gov/pubmed/22127230)