The Effect of -Hydroxy--Methylbutyrate on Aerobic Capacity and Body Composition in Trained Athletes

Durkalec-Michalski, K and Jeszka, J. The effect of -hydroxy--methylbutyrate on aerobic capacity and body composition in trained athletes. J Strength Cond Res 30(9): 2617-2626, 2016The aim of this study was to investigate whether supplementation with -hydroxy--methylbutyrate (HMB) affects body composition, aerobic capacity, or intramuscular enzymes activity, as well as in anabolic and/or catabolic hormones and lactate concentrations. A cohort of 58 highly trained males was subjected to 12-week supplementation with HMB (3 x 1 g(HMB<bold>)d(</bold>-1)) and a placebo (PLA) in randomized, PLA controlled, double-blind crossover trials, with a 10-day washout period. Body composition and aerobic capacity were recorded, whereas the levels of creatine kinase, lactate dehydrogenase, testosterone, cortisol, and lactate, as well as the T/C ratio, in blood samples were measured. After HMB supplementation, fat-free mass increased (+0.2 kg(HMB) vs. -1.0 kg(PLA), p = 0.021), with a simultaneous reduction of fat mass (-0.8 kg(HMB) vs. +0.8 kg(PLA), p < 0.001). In turn, after HMB supplementation, in comparison to PLA, maximal oxygen uptake (V..o(2)max: +0.102 L<bold>min(HMB)(</bold>-1) vs. -0.063 L<bold>min(PLA)(</bold>-1), p = 0.013), time to reach ventilatory threshold (VT) (T-VT: +1.0 min(HMB) vs. -0.4 min(PLA), p < 0.0001), threshold load at VT (W-VT: +20 W-HMB vs. -7 W-PLA, p = 0.001), and the threshold heart rate at VT (HRVT: +8 b<bold>min(HMB)(</bold>-1) vs. -1 b<bold>min(PLA)(</bold>-1), p < 0.0001) increased significantly. Analysis of the tested biochemical markers shows significant differences only in relation to the initial concentration. In HMB group, testosterone levels increased (p = 0.047) and in both groups (HMB: p = 0.008; PLA: p = 0.008) higher cortisol levels were observed. The results indicate that supplying HMB promotes advantageous changes in body composition and stimulates an increase in aerobic capacity, although seeming not to significantly affect the levels of the analyzed blood markers.