What are the Effects of B-hydroxy-B-methylbutyrate on Physical Capacity, Body Composition and Biochemical Markers in Endurance Training?
Title: 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 study
Author: Durkalec-Michalski et al
Journal: Journal of the International Society of Sports Nutrition
Objective: “to verify the effect of B-hydroxy-B-methylbutyrate (HMB) supplementation on physical capacity, body composition and the levels of biochemical markers in elite athletes practicing rowing.”
B-hydroxy-B-methylbutyrate, shorthand known as HMB, is a metabolite of the essential, branched chain amino acid leucine.
This metabolite was discovered approximately 20 years ago and holds special interest in the world of sports nutrition for it’s reported ability to increase muscle weight and strength. Previous studies have shown that supplementation lead to an increase in strength and fat free mass during resistance training.
These beneficial findings, may be in part due to the influence of HMB on the following pathways:
- de novo synthesis of cholesterol
- the expression of insulin-like growth factor 1 (IGF-1)
- the stimulation of the mTOR kinase pathway
- the ubiquitin-proteasome system and caspase activity
The authors of this study sought to evaluate the effects of B-hydroxy-B-methylbutyrate (HMB) on anaerobic training and it’s effects on physical capacity, body composition and biochemical markers.
16 elite male rowers were administered a 12-week HMB supplementation (1 gm HMB 3 times per day) and placebo administration following the model of a randomised, placebo controlled, double-blind crossover study with a 10 days washout period.
Aerobic capacity (maximal oxygen uptake, ventilatory threshold) and anaerobic capacity (anaerobic power indices) were determined, while analyses were conducted on body composition as well as levels of creatine kinase, lactate dehydrogenase, testosterone, cortisol and the T/C ratio.
Following HMB supplementation, VO2max increased (+2.7 mL · min −1 · kg −1 ) significantly (p < 0.001) in comparison to placebo administration (−1.0 mL · min −1 · kg −1 ).
HMB supplementation increased ventilatory threshold, threshold load and threshold heart rate compared to placebo administration.
Body fat mass decreased by nearly 1 kg on HMB, while it increased by nearly 1 kg on the placebo (−0.9 kg HMB vs. +0.8 kg PLA , p = 0.03).
After HMB supplementation, participants continued for an extended period of time in the progressive test (p = 0.04), increased their maximum load (p = 0.04) and anaerobic peak power (p = 0.02) increased.
No differences were observed in anaerobic adaptation or blood marker levels.
The study results suggest that HMB supplementation has a positive effect on anaerobic capacity and reduction in fat mass during endurance training.
It does not appear to have any effect on blood marker levels or anaerobic adaptation.
These results are relatively consistent with findings during research investigating it’s effects on resistance training.
Durkalec-Michalski, K., & Jeszka, J. (2015). 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 study. Journal of the International Society of Sports Nutrition, 12(1). doi:10.1186/s12970-015-0092-9