Daily supplements containing HMB, a metabolite of the branched chain amino acid leucine, may reduce fat mass and increase aerobic capacity in athletes training for endurance sports, says a new study.
Polish scientists report that a daily three gram dose of HMB (beta-hydroxy-beta-methylbutyric acid) for 12 weeks was associated with increased values of maximum oxygen uptake and indices of the ventilatory threshold. VT is believed to reflect the onset of the build-up of lactate and anaerobiosis.
Long-term HMB supplementation seems not only to have a significant effect on changes in activity of selected intramuscular enzymes testosterone and cortisol concentration, but also on values of the testosterone-cortisol ratio in blood,” wrote the researchers in the Journal of the International Society of Sports Nutrition .
Krzysztof Durkalec-Michalski and Jan Jeszka from the Poznan University of Life Sciences and the Polish Wrestling Federation recruited 16 elite male rowers with an average age of 20 to participate in their randomized, placebo controlled, double-blind crossover study. The men were randomly assigned to consume three grams per of HMB or placebo for 12 weeks. A two week washout period separated the two phases.
Results showed that HMB supplementation was associated with significant increases in VO2max, while this decreased during the placebo phase.
In addition, HMB extended the time required to reach VT in the men, said the researchers.
In terms of fat mass, HMB supplementation was associated with an average 0.9 kg decrease over 12 weeks, while the men gained an average of 0.8 kg during the 12-week placebo phase.
The results indicate that HMB intake in endurance training has an advantageous effect on the increase in aerobic capacity and the reduction of fat mass, wrote Durkalec-Michalski and Jeszka. It may also stimulate an increase in peak anaerobic power, while it seems to have no effect on other indices of anaerobic adaptation and levels of investigated markers in the blood.
The International Society of Sports Nutrition recently published a position paper on HMB in Journal of the International Society of Sports Nutrition as a nutritional supplement.
1.Krzysztof Durkalec-Michalski and Jan Jeszka, The efficacy of a β-hydroxy-β-methylbutyrate supplementation on physical capacity, body composition and biochemical markers in elite rowers: a randomised, double-blind, placebo-controlled crossover,J Int Soc Sports Nutr. 2015; 12: 31.