Beta-hydroxy-beta-methylbutyrate (HMB)
Last reviewed: 23.04.2024
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Main functions
- Increases muscle mass.
- Reduces the amount of adipose tissue.
- Increases strength and power.
Theoretical basis
Beta-hydroxy-beta-methylbutyrate (HMB) is a leucine metabolite with a branched-chain amino acid. Nissen et ai. It is believed that HMB is responsible for the well-known anti-catabolic actions of leu-din. HMB can partially interfere with the proteolysis and / or muscle damage caused by the load, and thus contribute to the increase in muscle mass and strength during training sessions with overcoming resistance.
Nissen et al. Suggested that HMB is a precursor of beta-hydroxy-beta-methylglutaryl-CoA (HMB-CoA) involved in the synthesis of cholesterol by muscle cells. They believe that muscle cells can not effectively use blood cholesterol and must produce it themselves. In stressful situations, muscle cells require more cholesterol to synthesize new cell membranes or regenerate damaged membranes of existing cells. Thus, HMB can make a difference during periods of stress, for example, during a resistance exercise, to enhance the integrity and function of muscle cells. To confirm this theory and refine the mechanism of action of HMB, further research is needed.
Research results
Data on the reduction of muscle proteolysis and the increase in muscle mass and strength are confirmed only by two studies published by the University of Iowa staff at the same time. In the first study, 41 untrained men (age 19-29 years old, average body weight - 82.7 kg) participated. Subjects were arbitrarily divided into three groups, which were given different amounts of HMB-Og (placebo), 1.5 g or 3.0 grams per day. In addition, they were also given one of two portions of protein: either normal - 117 g per day (1.4 g-kg1 or over-weighted - 175 g per day (2.1 g-kg1)). Subjects lifted the weights for 1.5 hours 3 times a week for 3 weeks.
Subjects receiving HMB supplements showed an increase in body weight corresponding to a 0.4 kg dose for the placebo group; 0.8 kg for the group taking 1.5 g of HMB and 1.2 kg for the group taking 3.0 g of HMB. The level of protein consumed did not affect the change in body weight or the amount of weight lifted. However, subjects who received HMB-doses increased the weight greater than those taking placebo for 3 weeks. The group receiving HMB supplements performed significantly more (by 50%) abdominal muscle exercises compared to the placebo group (14%). Overall strength (upper and lower body) increased significantly in both groups: in the group with 1.5 g of HMB - by 13%, in the group with 3.0 g of HMB - by 18.4%; in the group with placebo this value was 8%. When taking HMB, the muscular strength of the lower body is greater than the upper part of the body.
With the use of GM B, muscle damage is reduced. In urine, 3-methylhistidine (3-MG) decreased by 20%, and in the serum the activity of muscle creatine phosphokinase (CRP) and lactate dehydrogenase (LDH) decreased by 20-60%.
In the second study, the effect of HMB additives on changes in body composition and muscle strength over a longer period was studied: 32 trained men (aged 19-22 years, average body weight 99.9 kg) were arbitrarily divided into two groups. One received a placebo, another 3.0 grams of HMB per day. Subjects lifted the load for 2-3 hours daily 6 days a week for 7 weeks. On the 14th day and up to the 39th day, subjects who received supplements of HMB significantly increased lean mass compared to those who took placebo. On the last day of the study, the lean mass did not have significant discrepancies between the groups.
Recommendations
Athletes should not consider GMB a magic wand. Two studies were conducted by the same scientific group that developed the HMB. The results of the studies are of interest, but first they should be seriously analyzed.
Before using GMB additives, the following questions need to be considered.
- The results were not repeated by other researchers in other laboratories.
- Subjects of the first study Nissen et al. Were untrained, so the results can not be applied to trained people or elite athletes.
- Three weeks of GMB supplementation by untrained subjects increased their muscle mass compared to the placebo group slightly.
- Seven weeks of GMB supplementation by trained subjects did not increase their muscle mass in comparison with the group consuming placebo.
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