People who lose muscle mass following an illness or stress will know that it can be a frustrating experience. It is bad enough dealing with the illness itself but the knock on effects that your body must endure results in a double whammy of negativity.
Whilst it can be hard to rebuild the gains you once had, the scientific community provides some hope based on a recent animal study into HMB (1).
Two groups of mice; a test group and a control group, were implanted with a tumour so that they would undergo muscle loss. The test group were fed HMB on a daily basis whilst the control group were injected with saline (a standard sterile solution).
After three days of this treatment, the mice were dissected and their muscle tissue analysed. The levels of protein degradation (measured by tyrosine release) and protein synthesis (measured by uptake of phenylalanine) were assessed. In addition, the impact of an immunosuppressant chemical known as rapamycin, was also assessed on the HMB treated test group.
The tumour caused considerable loss of muscle mass due to i.) decreased protein synthesis and ii.) increased protein breakdown. Protein breakdown occurred due to a sequence of signals and HMB was found to interrupt these signals. The use of HMB also resulted in higher levels of protein synthesis. In addition, the use of the immunosuppressant rapamycin, negated the benefits of HMB on protein synthesis.
Levels of protein in muscle tissue are affected by numerous stressors, impacting both protein synthesis and protein breakdown. The use of HMB lowers the rate of muscle loss by preventing protein breakdown and increasing protein synthesis. However, HMB can be affected by other drugs such as rapamycin, which is sometimes used when undergoing surgery or in the treatment of cancer.
The study demonstrates the significant benefits of HMB in preventing muscle loss and also shows it may not be wise to use HMB in conjunction with immunosuppressant drugs.
Although the benefits of HMB are shown here in relation to people that have experienced muscle loss following an illness, previous research demonstrated HMB also has anti-catabolic effects for people that experience muscle loss due to intense exercise (2).
Furthermore, the benefits of HMB are not limited to the prevention of muscle loss. Research has also highlighted the positive impact that HMB can have on levels of fat free mass (3), thus HMB is a versatile supplement that provides scientifically proven benefits.
Based on the purported mechanism of action of HMB it is theorised it is most useful during stressful training periods such as when training volumes are high or when a large amount of eccentric work is performed.
In common with the research we previously discussed on HICA, this study shows again the value of metabolism of the branched chain amino acid, Leucine, for optimising body composition.
Future research directed towards comparing Leucine to its two metabolites would be beneficial to see if merely taking supplemental Leucine could have the same benefit.
1. Baxter, J., Mukerji, P., Voss, A., Tisdale, M. and Wheller, K. (2006). Attenuating Protein Degradation and Enhancing Protein Synthesis in Skeletal Muscle in Stressed Animal Model Systems. Medicine & Science in Sports & Exercise, 38(5), pS550-S551.
2. Knitter, A., Panton, L., Rathmacher, J., Petersen, A. and Sharp, R. (2000). Effects of β-hydroxy-β-methylbutyrate on muscle damage after a prolonged run. Journal of Applied Physiology, 89(4), 1340-1344.
3. Gallagher, P., Carrithers, J., Godard, M., Schulze, K. and Trappe, S. (2000). β-hydroxy-β-methylbutyrate ingestion, part I: Effects on strength and fat free mass. Medicine & Science in Sports & Exercise, 32(12), 2109-2115.
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