HMB increases training performance

HMB (beta-hydroxi-methylbutyrate) is a metabolic product of the amino acid lycine. More than 10 years ago, Nissen and colleagues (J. Appl. Physoil. 81: 2095-2104, 1996) showed that HMB prevents protein breakdown and promotes muscle hypertrophy in subjects training with weights. Other studies have shown that HMB increases lean body mass (primarily muscle) and reduces body fat mass. The combined simultaneous intake of HMB and creatine was more effective than taking either substance on its own.
However, numerous studies have concluded that HMB has no additional benefit for athletes. Researchers from Canada found that HMB improved maximal oxygen consumption (a measure of aerobic fitness) and facilitated breathing during exercise.
HMB is not as popular as creatine, but it has several beneficial effects that make it an effective bodybuilding supplement.
(International Journal Sports Nutrition Exercise Metabolism, 17: 56-69, 2007)