There are very few nutritional supplements that are worth taking, relative to the seemingly infinite amounts that are currently available on the market. Creatine stands out as one of the few that may be beneficial for athletes. Beta-hydroxy-beta-methylbutyrate (HMB) is a supplement that has generated a lot of debate in the strength and conditioning community based on conflicting results in a variety of studies. HMB is a metabolite of leucine, one of the branched chain amino acids primarily responsible for protein synthesis signaling. There is some evidence to suggest that HMB supports muscle growth and attenuates muscle break down. However, the majority of the research, both in support of and not, have many limitations that make the results unclear. For example, poor control of extraneous variables, non-monitored training programs, lack of control of diet, untrained subjects, etc. Thus, it has been difficult to ascertain whether this supplement is truly worthwhile.
In a recent issue of the European Journal of Applied Physiology, a study conducted by researchers at the University of Tampa was published that sought to determine how effective HMB is for improving strength, performance and body composition in resistance trained individuals. This was a double-blind, placebo-controlled study which is the gold standard for experimental research when attempting to establish cause and effect relationships. The placebo and control groups were age and training status matched with approximately 10 subjects in each group. Both groups performed the same training program over a twelve week period. The training program included 8 weeks of progressive training followed by a two week overreaching period, followed by a two week taper. One of the most impressive features of this study was the amount of control over extraneous variables that the researchers took. For example, a dietitian prescribed diets for all subjects that involved a macronutrient breakdown of approximately 25% protein, 50% carbohydrate and 25% fat.
The results were as follows:
The HMB group improved their bench, squat and deadlift strength (combined) 77.1 kg on average compared to the control group who improved strength by an average of 25 kg. The HMB group improved lean body mass by 7.4 kg compared to 6.1 kg in the control group. Vertical jump power in the HMB group was over 360 w higher than the control group at post-testing. In addition, HMB attenuated increases of creatine kinase and cortisol during the overreaching phase significantly more than control.
There are a number of factors that contribute to the novelty of this study. Perhaps most impressive was the tight controls over potential confounding variables, not controlled for in previous studies. Additionally, the use of resistance-trained individuals over a longitudinal training program really strengthens this study. It should be noted however that this study was partially funded by a company that manufactures the HMB product utilized in this study. That said, these were credible researchers from credible institutions that conducted this study. Further, the European Journal of Applied Physiology is a respected journal in this field. Overall, the results are quite compelling and certainly provides some convincing evidence to consider HMB supplementation to support training adaptations.
Wilson, J. M., Lowery, R. P., Joy, J. M., Andersen, J. C., Wilson, S. M., Stout, J. R., … & Rathmacher, J. (2014). The effects of 12 weeks of beta-hydroxy-beta-methylbutyrate free acid supplementation on muscle mass, strength, and power in resistance-trained individuals: a randomized, double-blind, placebo-controlled study. European journal of applied physiology, 114(6), 1217-1227.