HMB

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In the second of our series, we look at another supplement that not everyone is familiar with. This month, we focus on HMB. For experienced sports nutrition users, HMB is nothing new. If you’re new to sports nutrition, you may have heard of HMB, but not be overly familiar with its benefits.

HMB is an abbreviation of Beta-Hydroxy-Beta-Methylbutyrate (it’s easy to see why it has been abbreviated!) and is a metabolite of the Branched Chain Amino Acid, Leucine. The rationale behind HMB use is to reduce muscle breakdown, resulting in gains in size and strength. Indeed, a meta-analysis conducted by Nissen et al (2003) concluded that HMB was an effective sports supplement that improved strength and lean muscle gain, working as an anti-catabolic to spare muscle protein and speed recovery.

The above seems to pretty much sell it: an analysis of multiple studies demonstrating anti catabolism and improvements in strength. Unfortunately, there was always one ‘but.’ The one missing piece of research was on experienced lifters – a majority of the positive research was on novice trainers or specific populations, such as the elderly. Hoffman et al (2004) noted that the performance enhancing benefit of HMB is most likely to be in an untrained population, as the potential for muscle damage is highest.

Further research went on to suggest that HMB is of most benefit when muscle damage is highest. This doesn’t have to be for a novice trainer; anyone changing their training routine, exercise selection or intensity will be putting the body through unaccustomed exercise. There is where muscle damage and muscle soreness is most likely. In this instance, HMB could be of benefit.

Eccentric training has been shown to cause greater muscle damage than concentric training. So, for example, lowering the bar on the bench press creates more muscle damage than pressing it (assuming the bar is lowered in a controlled manner). For anyone who follows ‘time under tension’ principles with a controlled repetition tempo, HMB may attenuate muscle damage.

A recent study took twenty resistance trained males and investigated the role of HMB (Wilson, 2013) during high volume resistance training. HMB resulted in reduced muscle protein breakdown, reduced muscle damage and improved self perceived recovery. One factor of this particular study was the high volume training – it may be that early studies used a volume that was insufficient to demonstrate any potential benefit of HMB.

Interestingly, one study demonstrated a synergistic effect when HMB was combined with Creatine (Jowko, 2001). It could be theorised that the increased training volume that was possible due to Creatine supplementation created more muscle damage which, in turn, made HMB more beneficial.

The exact mechanisms of action are still being researched – increases in protein synthesis via the mTOR pathway have been shown. HMB may also inhibit the pathway responsible for the breakdown of intracellular proteins (Wilson, 2008).

In summary, if you train with high volume or are changing your training schedule and/or increasing intensity, HMB may help to reduce muscle breakdown and aid recovery. A recommended dosage is 3g per day; 1g should be taken three times daily, with one dose immediately after training.

References

Hoffman, J., Cooper, J., Wendell, M., Im, J & Kang, J. (2004) Effects of beta-hydroxy-beta-methylbutyrate on power performance and indices of muscle damage and stress during high intensity exercise. The Journal of Strength and Conditioning Research, 18, 747-752

Jowko, E., Ostaszewski, P, Jank, M., Sacharuk, J., Zieniewicz, A., Wilczak, J. & Nissen, S. (2001) Creatine and HMB additively increase lean body mass and muscle strength during a weight training program. Nutrition, 17, 558-566.

Nissen, S.L. & Sharp, R.L. (2003) Effects of dietary supplements on leans mass and strength gains with resistance exercise: a meta-analysis. Journal of Applied Physiology, 94, 651-659.

Wilson, G.J., Wilson, G.M & Manninen, A.H. (2008) Effects of HMB on exercise performance and body composition across varying levels of age, sex, and training experience: a review. Nutrition and Metabolism, 5, 1, 1

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