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Re: [RC] Lactic Acid - Jon . LindermanSince this is my field its sort of interesting to see this topic in popular press. Most physiology texts (human or quadriped) still use a simpleton's discussion of lactic acid (LA). Its not to say its wrong, just incomplete. I worked with one of the premier scientists on the topic in graduate school @ Berkeley, a man named George Brooks. Since the 70's hes published the most sophisticated work in the field, but due to the complexity of the issue, or his personality (fire on a gasoline pool) his work has been overlooked in more popular literature. It (LA) is a valuable tool in monitoring training or intensity of work, and as a powerful metabolic acid it does contribute to fatigue that we have known since the 50's. However, it is far far more complex than that. Basically a LA molecule is 1/2 of a glucose (sugar) molecule that still retains most of the energy of the glucose molecule & many tissues such as the heart, liver, and type I (slow twitch) muscle fibers use lactic acid as a fuel source. I imagine by the time I retire from academia there will be some progress in the general public's understanding, but it'll die slow, like the earth being flat or the earth being the center of the universe. One myth that will die very slowly is that LA is a toxin sitting in muscle days after exercise. Its gone w/in minutes to hours, used as a fuel source. If a mammal is fed or infused with LA during exercise it uses it as fuel & actually spares limited stores of glucose & glycogen the stored form of glucose. This has been show very conclusivel in rats, dogs, and humans. There are people who can not make LA, having a lack of one or more of the enzymes necessary & there work capacity is very very low. People (healthy or diseased) or animals on beta blockers can not make as much LA due to the effects of these drugs on metabolism & they also have limitations in work capacity as well. I helped do some work on a human sports drink that contained large quantities of LA back in the 80's, but lacking the vast resources of say Gatorade, issues of palatability, taste, etc, hampered its commercial appeal. Not even sure its still available. One of the problems studying the similarity of LA metabolism in horses, say compared to rats, dogs, and humans is the size of horses. The necessary tools or markers that are needed to perform this work are very expensive and the amounts needed in horses makes it astronomical. However, at the level of the cell, even the best scientists could not tell the difference between muscle cells in a rat, dog, horse, or human. There is no reason to suspect that the metabolism of LA is any different, but its not fully known. To my knowledge the best work in the area has been done by fomer colleagues, Ken Hinchcliff, Ray Geor, and some others at Ohio State. Time will tell. Remember Galileo and others were forced to recant there "theories" by the powers that be at that time: the Holy Catholic Church, for being heretical. Its much easier to hold onto popular misconceptions that provide simple answers, than to challenge beliefs. Glad to see people at least asking about the topic! Jon K. Linderman, Ph.D., FACSM Assistant 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/ "goearth" <goearth@xxxxxxxxxxx> To: "Jeannie Waldron" <jwaldron@xxxxxxxxx> Sent by: cc: "Ridecamp" <ridecamp@xxxxxxxxxxxxx> ridecamp-owner@xxxxxx Subject: [RC] Lactic Acid durance.net 08/24/2004 06:59 AM This may affect some minds from established thought. As reported in yesterdays Washington Post and quoted from this weeks issue of Science Magazine, says..." It is common wisdom among runners and other sports enthusiasts that lactic acid is the enemy of endurance. The chemical is a byproduct of metabolism during periods of intense exercise, when oxygen supplies cannot keep up with energy output. Its accumulation in work-stressed muscles has long been considered a major cause of achiness, exhaustion and failure. Now in an Olympian reversal, scientists have found that lactic acid actually enhances a tired muscle's ability to keep on twitching. The biochemistry and physiology that propel leaping legs and barbell-boosting arms start with a nerve impulse that delivers the mental demand for action and ends with a rush of electrically charged sodium, potassium, chloride, and calcium atoms into and out of cells in synchronized succession.... In the words of Science magazine, in whose Friday issue the new work appeared, lactic acid may be "the latest performance-enhancing drug." The new work does not prove that various strategies for reducing lactic acid buildup-such as drinking bicarbonate of soda or "warming down" muscles-are of no value to athletes, researchers said. But it may mean they work for reasons other than what was thought." ts =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Ridecamp is a service of Endurance Net, http://www.endurance.net. Information, Policy, Disclaimer: http://www.endurance.net/Ridecamp Subscribe/Unsubscribe http://www.endurance.net/ridecamp/logon.asp Ride Long and Ride Safe!! =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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