Possibly Effective β-hydroxy β-methylbutyrate (HMB) HMB is a metabolite of the amino acid leucine. Leucine and metabolites of leucine have been reported to inhibit protein degradation [110]. Supplementing

the diet with 1.5 to 3 g/d of calcium HMB during training has been typically reported to increase muscle mass and strength particularly among untrained subjects initiating training [111–116] and the elderly AG-881 solubility dmso [117]. Gains in muscle mass are typically 0.5 to 1 kg greater than controls during 3 – 6 weeks of training. There is also evidence that HMB may lessen the catabolic effects of prolonged exercise [118, 119] and that there may be additive effects of co-ingesting HMB with creatine [120, 121]. However, the effects of HMB supplementation in athletes are less clear. Most studies conducted on trained subjects have reported non-significant gains in muscle mass possibly due to a greater variability in response of HMB supplementation among athletes [122–124]. Consequently, there is fairly good evidence showing that HMB may enhance training adaptations

in individuals initiating training. LY333531 chemical structure However, additional research is necessary to determine whether HMB may enhance training adaptations in trained athletes. Branched Chain Amino Acids (BCAA) BCAA supplementation has been reported to decrease exercise-induced protein degradation and/or muscle enzyme release (an indicator of muscle damage) possibly by promoting an anti-catabolic hormonal profile [31, 51, 125]. Theoretically, BCAA supplementation during intense training may help minimize protein degradation and thereby lead to greater gains in fat-free mass. There is some evidence to support this hypothesis. For example, Schena and colleagues [126] reported that BCAA N-acetylglucosamine-1-phosphate transferase supplementation (~10 g/d) during 21-days of trekking at altitude increased fat free mass (1.5%) while subjects ingesting a placebo had no change in muscle mass. Bigard and associates [127] reported that BCAA supplementation appeared to minimize loss of muscle mass in subjects training at altitude for 6-weeks. Finally, Candeloro and coworkers [128] reported that 30 days of BCAA supplementation (14 grams/day) promoted a significant increase in muscle

mass (1.3%) and grip strength (+8.1%) in untrained subjects. A recent published abstract [129] reported that resistance trained subjects ingesting 14 grams of BCAA during 8 weeks of resistance training experienced a significantly greater gain in body weight and lean mass as compared to a whey protein supplemented group and a carbohydrate placebo group. Specifically, the BCAA group gained 2 kg of body mass and 4 kg of lean body mass. In contrast, the whey protein and carbohydrate groups both gained an additional 1 kg of body mass and 2 kg and 1 kg of lean body mass, respectively. It cannot be overstated that this investigation was published as an abstract, was conducted in a gym setting, and has not undergone the INK1197 rigors of peer review at this time.