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			Branched-chain amino acid supplementation has been reported to decrease exercise-induced protein degradation and/or serum muscle enzyme efflux,[30-32] possibly by promoting an anticatabolic hormonal profile.[13,15] Theoretically, branched chain amino acid supplementation during intense training may help minimise protein degradation and thereby lead to greater gains in fat-free mass.[22,29,33,34]
In support of this contention, Carli and associates[13] reported that addition of 10g of branched chain amino acid to a carbohydrate/protein drink promoted a more anabolic response to intense running compared with ingesting the carbohydrate/protein supplement without branched chain amino acid. Moreover, Coombes and McNaughton[31] reported
that branched chain amino acid supplementation (12 g/day for 14 days) prior to performing a 2-hour period of endurance cycling at 70% of maximal oxygen uptake, significantly decreased postexercise creatine kinase and lactate dehydrogenase (LDH) enzyme efflux. This suggests that branched chain amino acid supplementation may reduce exercise-induced muscle damage. Mourier et al.[33] found that branched chain amino acid supplementation during 19 days of calorie restriction in wrestlers promoted a greater reduction in percent body fat while maintaining fat-free mass to a greater degree compared with athletes on hypocaloric control, hypocaloric low protein, and hypocaloric high protein diets. Finally, we reported that branched chain amino acid supplementation with carbohydrate during 25 weeks of swim training promoted a greater increase in fat-free mass and reduction in percent body fat compared with carbohydrate supplementation alone.[22,23]
Although results of these studies support contentions that branched chain amino acid supplementation may affect protein degradation and/or muscle mass, none of these studies evaluated the effects of branched chain amino acid supplementation on body composition alterations during resistance training. Consequently, additional research is necessary to determine whether branched chain amino acid supplementation prior to and/or following resistance-exercise promotes muscle growth.