Welcome to the Sports Dietitians Australia factsheets! We encourage you to use the factsheets to further your understanding of these specific areas of sports nutrition but please note that the information they contain is general in nature. We all have different physical needs and attributes. This means that while there are general principles, the key to sports nutrition is that it is very individual in nature. For this reason, not all factsheets are publicly available and are accessible only to members. For support that is specific to your activity needs and health and stage of life requirements, please reach out to an Accredited Sports Dietitian.
What is HMB?
b-Hydroxy b-methylbutyrate (HMB) is a metabolite of the branch chain amino acid leucine. It is claimed that HMB decreases muscle protein breakdown and increases muscle mass and strength development and reduces muscle damage/soreness.
HMB and Performance
Interest in HMB within sport emerged following the publication of research suggesting greater resistance training adaptations in response to HMB supplementation. Researchers reported that supplementation with either 1.5 or 3.0 g per day of HMB had a favourable impact on muscle protein breakdown and muscle damage, with trends for enhanced strength and hypertrophy. However, when data is combined across several studies, the benefits of HMB supplementation in response to resistance training tend to be trivial for untrained individuals and even less beneficial in trained lifters.
Recommended dosing strategy
HMB has a relatively short half-life in the blood and so is typically prescribed in small doses of split across the day.
Potential risks or side effects in taking HMB
Short term HMB supplementation appears to be safe. No studies on the safety of long term HMB supplementation have been undertaken although acute large doses appear to be free of side effects, as does an intake of 3 grams per day.
Summary
The potential for HMB supplementation to enhance strength training adaptations appears to be small in untrained individuals and negligible in trained athletes. Given that the protein synthetic response is much more sensitive to nutrition interventions than protein breakdown, athlete is advised to focus on proven strategies such as post-exercise ingestion of high biological value proteins rich in leucine to maximize adaptation to the resistance training stimulus. Speak to your local Accredited Sports Dietitian if you want to learn more.
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