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HMB
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{{DISPLAYTITLE:HMB For Runners}}
HMB is a supplement that may help preserve muscle during weight loss, something that is typically quite difficult. It may also be valuable for those who struggle to maintain weight during heavy training. HMB might improve fat loss, increase muscle gain, and there's slight evidence that it might increase aerobic performance. HMB appears safe at the recommended doses and is not banned. HMB should be taken to time with periods when muscles loss may occur, such as exercise or fasting. I would be cautious about taking HMB before a critical race, as the breakdown of muscle may provide a valuable energy source.
=What is HMB?=
HMB, or "β-Hydroxy β-methylbutyric acid" to give it its full name<ref name="HMBPubChem"/>, is naturally produced in the body as the amino acid leucine is metabolized<ref name="MolfinoGioia2013"/>. It's been shown that leucine controls protein synthesis and metabolism<ref name="NortonLayman2006"/>, and it seems that one mechanism of action is via the HMB metabolite<ref name="NissenSharp1996"/>. My personal interpretation is that HMB tricks the body into acting as if it had consumed large quantities of protein, activating protein synthesis and inhibiting protein metabolism.
* HMB inhibits muscle breakdown (proteolysis) after training<ref name="NissenSharp1996"/>, in old age<ref name="WuXia2015"/>, bed rest<ref name="DeutzPereira2013"/>, and muscle wasting conditions such as AIDS and cancer<ref name="Hasselgren2014"/>. Most importantly for athletes, HMB reduces muscle loss during calorie restricted training<ref name="ParkHenning2013"/>.
* HMB reduces muscle damage after endurance running (20Km/13 miles)<ref name="KnitterPanton2000"/>.
* HMB enhances the fat lose effects of exercise<ref name="StoutFukuda2015"/>. There is some evidence that HMB directly increases fat loss (lipolysis), though the only reference I could find to this is in a patent<ref name="Rathmacher2016"/>.
* Not only does HMB reduce protein losses, it also increases protein synthesis, even in fasting subjects<ref name="WilkinsonHossain2013"/>. Subjects in that study were recreationally active, but not formally training. They did not perform heavy exercise for 72 hours and were overnight fasted. This is really interesting as it indicates that HMB can improve protein synthesis in the absence of recent exercise stress or protein intake.
* HMB may improve some markers of cardiovascular health, such as blood pressure and LDL cholesterol<ref name="NissenSharp2000"/>.
* There's some evidence from animal studies that HMB may reduce insulin resistance<ref name="SharawyEl-Awady2016"/><ref name="FuBruckbauer2015"/>, though in high doses (equivalent of >50g/day in humans) one study found increased insulin resistance<ref name="YonamineTeixeira2014"/>.
* HMB doesn't raise insulin levels<ref name="WilkinsonHossain2013"/>, unlike protein, so it doesn't inhibit fat loss (lipolysis.) This is critical given it's its use to improve fat loss. * I found one study that showed two weeks of HMB reduce [[Lactate]] accumulation and increased VO<sub>2</sub> at 2 mM Lactate after <ref name="VukovichDreifort2001"/>. Personally, I suspect any improvement is probably due to changes in body composition. * The commonly used dose of HMB is 1g given 3 times a day. I could find no research that established this is the right dose as few studies compare multiple levels.
* HMB is surprisingly cheap; buying in bulk from amazon.com (see below) costs less than $0.10 per dose (1 gram.)
=How I take HMB =
This isn't medical advice, just my approach that you can use as a starting point. I'm continually tweaking my training and nutrition, so by the time I've finished writing this it's likely to be slightly different! My approach assumes I'm trying to reduce my body fat while keeping or increasing lean mass, which is fairly normal for me. If you're one of the athletes who has trouble maintaining or gaining weight then your approach is likely different. The calcium form of HMB (the cheapest and most widely tested) peaks in the blood about 30 minutes after consumption<ref name="WilkinsonHossain2013"/>, and has a half-life of about 2.5hours<ref name="FullerSharp2010"/>. This means that timing seems to be pretty important.
* I don't follow the standard recommendation of 1g, 3 times per day. I did that initially, and I seem to have much better results by timing the doses more carefully based on the research. I'm also typically taking more than the 3g/day.
* I've found that intermittent fasting (IF) seems to work best for me to lose weight or just keep my weight under control. I often joke I have the genes of a natural athlete, but sadly my natural sport is sumo wrestling. I tend to use the 16:8 pattern of 16 hours of fasting and 8 hours of eating. However, this is a little modified depending on training. I typically break my fast mid-late morning.
* My nutrition during the run varies, but typically I refuel every 60-120 minutes. Sometimes my "fuel" will be just an HMB/Vitamin C dose in an electrolyte drink, but doing a marathon+ length training run without calories is tough. I'll often take 5-10g of whey protein as fuel, which makes a huge difference (possibly placebo) to my performance. If I'm feeling the need, often on back to back marathon+ days I'll add 5-10g sugar to the mix. My aim is to stay in sufficient calorie deficit that I can convince myself I'm still fasting.
* What I do at the end of the run depends on timing. If I'm ready to end the fast, I'll typically make a hot chocolate with 1 tablespoon pure cocoa, 25g whey, and 8oz of milk. If the fast is continuing then it will just be HMB and vitamin C.
* Excluding the start and end of the fast I aim to eat a variety of foods that are nutrient dense, focusing on vegetables and fruit, along with dairy and eggs. I have a very low meat intake, generally once a week or so.
* I finish my eating period with Casein protein, milk, and sometimes eggs, but without HMB. My goal is to have a supply of protein available for the early part of the fast, including the initial sleep period.
* I take an HMB & Vitamin C dose just before sleeping, typically 1-3 hours after starting the fast. This is to keep the HMB levels up overnight to prevent muscle metabolism.
<ref name="WilkinsonHossain2013">D. J. Wilkinson, T. Hossain, D. S. Hill, B. E. Phillips, H. Crossland, J. Williams, P. Loughna, T. A. Churchward-Venne, L. Breen, S. M. Phillips, T. Etheridge, J. A. Rathmacher, K. Smith, N. J. Szewczyk, P. J. Atherton, Effects of leucine and its metabolite β-hydroxy-β-methylbutyrate on human skeletal muscle protein metabolism, The Journal of Physiology, volume 591, issue 11, 2013, pages 2911–2923, ISSN [http://www.worldcat.org/issn/00223751 00223751], doi [http://dx.doi.org/10.1113/jphysiol.2013.253203 10.1113/jphysiol.2013.253203]</ref>
<ref name="ReitelsederAgergaard2011">Søren Reitelseder, Jakob Agergaard, Simon Doessing, Ida C. Helmark, Peter Lund, Niels B. Kristensen, Jan Frystyk, Allan Flyvbjerg, Peter Schjerling, Gerrit van Hall, Michael Kjaer, Lars Holm, Whey and casein labeled with l-[1-13C]leucine and muscle protein synthesis: effect of resistance exercise and protein ingestion, American Journal of Physiology-Endocrinology and Metabolism, volume 300, issue 1, 2011, pages E231–E242, ISSN [http://www.worldcat.org/issn/0193-1849 0193-1849], doi [http://dx.doi.org/10.1152/ajpendo.00513.2010 10.1152/ajpendo.00513.2010]</ref>
<ref name="Rathmacher2016"> Rathmacher, John, Naji Abumrad, and Shawn Baier. "Compositions and Methods of Use of-hydroxy--methylbutyrate (HMB) for Decreasing Fat Mass." U.S. Patent Application No. 15/170,329.</ref>
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