HMB, or β-hydroxy-β-methylbutyrate, has received a lot of attention over the years. In our recent article in The Supplement, we looked at some of the research on HMB. In particular, research on reducing muscle breakdown and muscle damage was discussed. A recent study, published in the June edition of the Journal of Physiology, reinforced these findings.
Many people have commented that as HMB is a Leucine metabolite and, as such, there could be little point in using both – i.e. just Leucine would be sufficient. Wilkinson et al (2013) compared the effects of 3.42g of both HMB and Leucine. The researchers were particularly interested in looking at signaling for muscle growth and markers of muscle breakdown. Interestingly, both HMB and Leucine increased signaling for muscle growth (mTOR), although this was more pronounced with Leucine. HMB also reduced muscle breakdown by 57%. The authors concluded that both HMB and Leucine could result in muscle growth, but via different mechanisms of action.
Another study published this year, looked at the effects of HMB on inflammatory markers in trained resistance athletes. This study is of particular relevance as the subjects were familiar with resistance training – the subjects were elite paddlers. Typically, it’s far harder to see results in an elite population. Ferreira et al (2013) found that subjects in the HMB supplementation group (daily intake of 37.5mg per kilogram of bodyweight- so 3g for an 80g person) significantly increased lean body mass and reduced markers of muscle damage, such as Creatine Kinase. Vitally, for an elite population, this translated into an improvement in official race time.
Simply, HMB and Leucine work in different ways. To reduce muscle breakdown and muscle damage, HMB appears to be the better choice. Leucine may be the better choice to increase protein synthesis. This reinforces our previous article, where we suggested that HMB may be of additional benefit during periods of hard training.
Ferreira, H, R., Rodacki, A,L,F., Gill, P., Tanhoffer, R., Filho, J, F., Fernandes, L.C. (2013) The Effects of Supplementation of or β-hydroxy-β-methylbutyrate on Inflammatory Markers in High Performance Athletes, Journal of Exercise Physiology, 16, 1
Wilkinson, D., Hossain, T., Hill, D.S., Phillips, B.E., Crossland, H., Williams, J., Loughna, P., Churchward-Venne, T.A., Breen, L., Phillips, S.M., Etherbridge, T., Rathmacher, A., Smith, K., Szewczyk, N.J. & Atherton, P.J. (2013) Effects of Leucine and it’s metabolite β-hydroxy-β-methylbutyrate on human skeletal muscle protein metabolism. The Journal of Physiology, 591, 11, 2911-2923.