Maximizing your adaptations to a specific training stimulus really comes down to managing two specific and somewhat contrasting concepts.
The first is maximizing the synthesis of new muscle protein. This is how your muscles repair from the damage and stress of training, and how you ultimately get stronger, faster, more powerful, and more athletic.
The second is reducing excessive muscle damage on the front end of training while simultaneously limiting the total catabolism (breakdown) of muscle protein. If your body is more efficient with every single muscle action and muscle contraction during training so muscle damage is reduced, then the body has less damage to recover from.
Pairing up these two aspects of the muscle protein spectrum, i.e., stimulating the production of new muscle protein, and preventing muscle breakdown is the only way to reach your full athletic potential. We know that the amino acid Leucine is the most potent nutrient-specific stimulator of muscle protein synthesis, and thus addresses the first concept mentioned previously, but what nutrients are available and specific to the second concept? 
Until recently, the only real option to prevent excessive muscle breakdown and total catabolism was to ingest lots, and lots, and lots of protein on a daily basis. For some people, a high protein diet is still somewhat of a struggle. The good news for everyone is that a specific active metabolite of Leucine, called HMB (Beta-Hydroxy Beta-Methylbutyrate), has been shown to reduce the breakdown of muscle protein and thus can have a very potent anti-catabolic effect for muscle tissue. The extent that HMB will affect your ability to train more by reducing the total damage your body has to deal with is still not completely clear. At this point in time, we only have a few studies on trained individuals, but I personally have high hopes for this unique supplement ingredient.
Two studies conducted at the University of Tampa on a specific type of HMB, called HMB-Free Acid (HMB-FA), have shown some pretty amazing results in both the short and long-term window. The first study on HMB-FA examined the effects on perceived recovery status (how “recovered” the study subject felt), concentration of creatine kinase (a marker of muscle damage) and a few other variables including cortisol and testosterone.
This 1-day study showed that when this type of HMB was given to trained athletes, prior to intense, high-volume training, they felt more recovered and had significantly less muscle damage as evidenced by less creatine kinase in comparison to the placebo.
The second study assessed the effects of HMB-FA over the course of a 12-week high-volume training program. The 12 weeks were broken down into phases, with phase one consisting of 8 weeks of periodized resistance training, phase two consisting of 2 weeks of an overreaching cycle, and phase three consisting of a 2 week taper. The results of this study were that HMB-FA “enhances hypertrophy, strength, and power following chronic resistance training, and prevents decrements in performance following the overreaching.”
As amazing as these results are, we still have only a tiny glimpse of what the full HMB picture is. The few other studies conducted on HMB and trained athletes show little or no significant effect (some show trends toward significance), which means we need more research in this specific area.
At this point in time, I recommend adding in an HMB supplement during high-volume phases of training, such as an overreaching phase. I am not yet convinced it is absolutely necessary to take HMB both in-season and out of season, though research in the future may shed more light. In the same way that you add layers of clothing during the specific time of the year when the temperature gets colder, HMB may be a supplement to add into your dietary arsenal when you are about to start significantly increasing the amount of training, reps, sets, and total work.
The idea that HMB can provide the potential for more training volume is appealing to every type of athlete, since training volume is the variable most closely correlated to athletic performance. It may be the next big thing. Until we have a larger body of published evidence to work with, give it a try and share your experience!
References
Wilson, Jacob M., Ryan P. Lowery, and Jordan M. Joy. “β-Hydroxy-β-methylbutyrate Free Acid Reduces Markers of Exercise-induced Muscle Damage and Improves Recovery in Resistance-trained Men.” British Journal of Nutrition 110.03 (2013): 538-44. Web.
The Effects of 12 Weeks of Beta-hydroxy-beta-methylbutyrate Free Acid Supplementation on Muscle Mass, Strength, and Power in Resistance-trained Ind…” National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 21 Oct. 2016.
Gallagher, Philip M., John A. Carrithers, Michael P. Godard, Kimberley E. Schulze, and And Scott W. Trappe. “??-hydroxy-??-methylbutyrate Ingestion, Part I: Effects on Strength and Fat Free Mass.” Medicine and Science in Sports and Exercise 32.12 (2000): 2109-115. Web
http://examine.com/supplements/HMB/
About Kevin Kuhn
Kevin Kuhn, M.S.Ed., CSCS, MFS is a Kinesiologist and Sport Nutrition Coach in Dallas, Texas. Before moving to Dallas in 2012, Kevin was the head strength & conditioning coach for the Indiana Invaders professional running club in Indianapolis, Indiana. Kevin specializes in athletic performance with great interest and experience in running-specific strength & conditioning, corrective exercise, and exercise and sport nutrition. Kevin has been certified by the National Strength & Conditioning Association as a Certified Strength and Conditioning Specialist (CSCS) and as a Master Fitness Specialist by the Cooper Institute.
Free Training Guides!
Sign up for the newsletter, get your FREE eBooks, and receive weekly updates on cutting edge training information that will help take your knowledge of athletic performance to a new level.