Supplementation with the bodybuilding supplement HMB – full name beta-hydroxy-beta-methyl-butyrate – inhibits catabolic processes and stimulates anabolic processes thus helping bodybuilders and other strength athletes in other ways besides pure muscle development. Sports scientists at the University of Central Florida discovered that HMB also boosts the production of growth hormone and IGF-1 during resistance training.
HMB [structural formula on the right] is a metabolite of leucine. In the 1990s Steve Nissen discovered that daily supplementation consisting of a couple of grams of HMB helped bodybuilders to gain kilograms of muscle mass within three weeks. Nissen set up, together with fellow researchers, the company Metabolic Technologies to market HMB. The company continuously finances studies which show that HMB works. The study in this posting was also sponsored by Metabolic Technologies.
The researchers did an experiment with 20 male students, all of whom had been doing strength training for a couple of years. They put the men through their paces with leg training exercises: squats, dead-lifts and split-squats.
Half of the men took 1 g HMB Free Acid 30 minutes before the training session; the other half were given a placebo. The researchers took blood samples from the men just before they started the workout and half an hour after it had finished. In the lab they then measured the amount of anabolic hormones such as testosterone, insulin, growth hormone and IGF-1 present in the blood.
HMB supplementation had no effect on insulin and testosterone, but did have an effect on growth hormone and IGF-1, as the figures below show.
The researchers used capsules of HMB Free Acid which contained a gel. “A recent study found no differences in absorption between HMB Free Acid and HMB-Ca [the calcium bound HMB that is found in most HMB supplements] in the animal model when both forms were administered in liquid suspension”, the researchers wrote. “Thus, the gel form of HMB Free Acid may be responsible for its observed salient features.”
“It is important to note that since we did not use HMB-Ca in the current study for comparison, further investigations examining various forms of HMB Free Acid and HMB-Ca are needed to translate findings to a trained human population.”
Effects of ?-Hydroxy-?-methylbutyrate Free Acid Ingestion and Resistance Exercise on the Acute Endocrine Response.
Objective. To examine the endocrine response to a bout of heavy resistance exercise following acute ?-hydroxy-?-methylbutyrate free acid (HMB-FA) ingestion. Design. Twenty resistance trained men were randomized and consumed either 1?g of HMB-FA (BetaTor) or placebo (PL) 30?min prior to performing an acute heavy resistance exercise protocol. Blood was obtained before (PRE), immediately after (IP), and 30?min after exercise (30P). Circulating concentrations of testosterone, growth hormone (GH), insulin-like growth factor (IGF-1), and insulin were assayed. Data were analyzed with a repeated measures ANOVA and area under the curve (AUC) was analyzed by the trapezoidal rule. Results. The resistance exercise protocol resulted in significant elevations from PRE in testosterone (P < 0.01), GH (P < 0.01), and insulin (P = 0.05) at IP, with GH (P < 0.01) and insulin (P < 0.01) remaining elevated at 30P. A significant interaction was noted between groups in the plasma GH response at IP, which was significantly higher following HMB-FA compared to PL (P < 0.01). AUC analysis revealed an elevated GH and IGF-1 response in the HMB-FA group compared to PL. Conclusion. HMB-FA prior to resistance exercise augments the GH response to high volume resistance exercise compared to PL. These findings provide further support for the potential anabolic benefits associated with HMB supplementation.
PMID: 25792982 [PubMed] PMCID: PMC4352513