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HMB
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* 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 may improve wound healing, though I only found one study that used HMB and two amino acids (arginine & glutamine) on elderly subjects<ref name="WilliamsAbumrad2002"/>.
* I expected HMB to improve tendon healing, but I found no research in this area. There is a patent for using HMB to improve tendon healing, but it's based on case studies only<ref name="Patent-US20170071886A1"/>.
* 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 =
* 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. (Protein intake before sleep has been shown to increase muscle protein synthesis<ref name="SnijdersTrommelen2019"/>.)
* 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.
* Depending on how I'm feeling, I sometimes take a dose of HMB in the middle of the night.
Since it's first use as a nutritional supplement in 1997, HMB has been extensively studied, and found to be safe in both human and rodents<ref name="WilsonFitschen2013"/>. There was one study that found high doses of HMB, the equivalent of over 50g/day in humans, increased insulin resistance<ref name="YonamineTeixeira2014"/>, though other studies show improved insulin resistance at typical levels (see above). However, contamination of supplements is an issue, with at least one athlete testing positive due to taking an HMB supplement<ref name="wada"/>.
=Casein or Whey?=
On a related topic, should you use whey or casein protein? (I'll ignore other types of protein for now.) I'd like to think that using Casein can extend the fat burning into this early part of the post-fast, but I'm not sure the research supports my optimism. Certainly, casein has a lower insulin response than whey<ref name="ReitelsederAgergaard2011"/>. That study compared 0.3 g/kg lean body mass of whey or casein in healthy subjects (that's just ~17g.) The casein resulted in a lower insulin response from 15 to 60 minutes, with a peak insulin of ~110 (casein) v 180 (whey), both pmol/L. The total insulin response (area under the curve) was 15.6 for casein v 18.5 for whey. It's not clear that the difference would change the impact on fat burning (lipolysis.) It only required requires 12 pmol/L of insulin to suppress 50% of lipolysis, 22 pmol/L to suppress 70%, and 34 pmol/L to suppress 90%<ref name="JensenCaruso1989"/>. This suggests that the difference between casein and whey isn't going to impact lipolysis.
[[File:Insulin Casein Whey.jpg|center|thumb|400px|]]
For a sense of how insulin changes during exercise, a study of trained cyclists exercising while fasted at 74% [[VO2max|V̇O<sub>2</sub>max]] for 2 hours found their insulin levels dropped from 14.3 to 10.7 pmol/L after 30 minutes then remained around 8-6-9.7 pmol/L<ref name="CoyleHagberg1983"/>. When given carbohydrate at 1.0g/Kg at the start, then 0.25g/Kg at 60 and 90 minutes, their insulin remained around 13-15 pmol/L. (1.0 g/Kg was ~70g or 280 Calories, 0.5 g/Kg was ~17g or 70 Calories for the subjects.)
=Support This Site=
This is the HMB powder I use; it's the calcium form, which is much cheaper and more widely studied than the free acid.
<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>
<ref name="CoyleHagberg1983">E. F. Coyle, J. M. Hagberg, B. F. Hurley, W. H. Martin, A. A. Ehsani, J. O. Holloszy, Carbohydrate feeding during prolonged strenuous exercise can delay fatigue, Journal of Applied Physiology, volume 55, issue 1, 1983, pages 230–235, ISSN [http://www.worldcat.org/issn/8750-7587 8750-7587], doi [http://dx.doi.org/10.1152/jappl.1983.55.1.230 10.1152/jappl.1983.55.1.230]</ref>
<ref name="SnijdersTrommelen2019">Tim Snijders, Jorn Trommelen, Imre W. K. Kouw, Andrew M. Holwerda, Lex B. Verdijk, Luc J. C. van Loon, The Impact of Pre-sleep Protein Ingestion on the Skeletal Muscle Adaptive Response to Exercise in Humans: An Update, Frontiers in Nutrition, volume 6, 2019, ISSN [http://www.worldcat.org/issn/2296-861X 2296-861X], doi [http://dx.doi.org/10.3389/fnut.2019.00017 10.3389/fnut.2019.00017]</ref>
<ref name="WilliamsAbumrad2002">Jeremy Z. Williams, Naji Abumrad, Adrian Barbul, Effect of a Specialized Amino Acid Mixture on Human Collagen Deposition, Annals of Surgery, volume 236, issue 3, 2002, pages 369–375, ISSN [http://www.worldcat.org/issn/0003-4932 0003-4932], doi [http://dx.doi.org/10.1097/00000658-200209000-00013 10.1097/00000658-200209000-00013]</ref>
<ref name="Patent-US20170071886A1">Baier, Shawn, Naji Abumrad, and Emily Harris. "COMPOSITIONS AND METHODS OF USE OF ß-HYDROXY-ß-METHYLBUTYRATE (HMB) FOR ENHANCING RECOVERY FROM SOFT TISSUE TRAUMA." U.S. Patent Application No. 15/267,717.</ref>
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