Effects of β-hydroxy β-methylbutryate (HMB) supplementation on
testosterone and cortisol concentration of athletes: A systematic review
and meta-analysis of randomized controlled trials
Abstract
Background: β-hydroxy β-methylbutryate (HMB) is a metabolite of leucine
amino acid and it has several ergogenic benefits. Previous studies also
showed that it may affect beneficially the testosterone and cortisol
concentration in athletes. Due to the contradiction results between
studies, we aimed to conduct this meta-analysis to assess the HMB
supplementation effect on testosterone and cortisol in trained athletes.
Methods: Scopus, Medline and Google scholar were systematically searched
up to August 2020. The Cochrane Collaboration tool for evaluating the
risk of bias was applied for assessing the studies quality. Random
effects model, weighted mean difference (WMD), and 95% confidence
interval (CI) were used for estimating the overall effect. Between-study
heterogeneity was evaluated applying the chi-squared and I2 statistic.
Results: Seven articles were included in the meta-analysis. Although,
the meta-analysis generally showed that HMB consumption did not have any
effect on the cortisol and testosterone concentration (P >
0.05), but subgroup analysis based on the exercise type, showed a
significant decrease in the cortisol concentration in resistance
training exercises (WMD= -3.30; 95% CI: -5.50, -1.10; P= 0.003) and a
significant increase in the testosterone concentration in aerobic and
anaerobic combined sports (WMD= 1.56; 95% CI: 0.07, 3.05; P= 0.040).
Conclusion: The results indicate that HMB supplementation in athletes
can reduce the concentration of cortisol in resistance exercises and
increase the concentration of testosterone in aerobic and anaerobic
combined exercises. Nevertheless, more studies are required to confirm
these results.