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Re: [RC] Lactic Acid - Jon . Lindermanhmm, where to start without giving you my whole dissertation from 1990. First, where does lactic acid come from? Answer, glycolysis, or the "lysing" breaking down of glucose molecules. It is NOT a matter of symantics but glycolysis does not REQUIRE oxygen, and to be even more complex some fibers are more suited to glycolysis than others by design. Its not novel that lactic acid is a fuel. IN the 1950's Margaret CorI and her husband earned the Nobel prize for thier work in this area, and George Brooks advanced this idea in the 1980's at Berkley. When glycolysis occurs and lactic acid is formed MOST of the potential energy in the glucose molecule remains in the lactate (negative ion) and can be used as energy by fiberss/cells mor suited to oxidative metabolism. Is lactic acid bad? Yes and no. The dissocation of lactic acid to lactate and its proton, the acid, is very favorable from a Biochemical perspective, so when large amounts of lactic acid are formed when cells/fibers are called upon during very intense work (>75-80% of maximal effort) the pH of blood and muscles decreases. The acidic condition decreases the activity of enzymes & stimulates afferent (feeling) nerves and you say "ouch"! However, during more moderate to lower intensity activity the rate of removal (use) prevents build up, which is different than the cute fairly tale that says when blood lactic acid is low we don't make it....hog wash, we clear (use) it. So yes lactic acid, and many of its ascribed evils exist, the part textbooks remain resistant to is the much more complex manner that it is of value as a carbon shuttle, and as a usable energy source. Look we've known this since 1950 and even mroe indepth since 1980, but most people enjoy the simple black and white definition.......by the way as you sit here reding my post you are actually (GASP!) making some lactic acid........are you huritng, "run out of oxygen"?? You are just clearing it as rapidly as you make it and so it hasn't built up in your blood or muscles. Okay, I got long winded, but for me, its actually pretty short on this topic. Bottom line its very very complex. Who do you choose to trust Betty the aerboics instructor or a Nobel laureate? Jon K. Linderman, Ph.D., FACSM
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Associate Professor of Health and Sport Science University of Dayton 300 College Park Dayton, OH 45469-1210 Voice:(937) 229-4207 FAX: (937) 229-4244 http://homepages.udayton.edu/~lindermj/
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