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.

For more information on this or other sports nutrition topics, subscribe to our newsletter or book to see an Accredited Sports Dietitian.