This article (click image to enlarge; Br J Sports Med, 15 Dec 2010, epub ahead of print) shows that faster marathoners tend to drink less than slower marathoners when racing, but that fluid intake is all over the map, with high and low drinkers in both the fast and slow categories (no data is presented on fluid intake during regular training). The principle investigator for the research, Tim Noakes, has long been a proponant of low fluid intake during exercise because excess fluids (gaining weight during a race!) can lead to hyponatremia. But this study does not address what would happen to anyone's performance time if they drank more. To do that, you would have to have the SAME ATHLETES run a marathon TWICE to compare their performance with two different levels of hydration.
Imagine if you had a friend that told you his Ferrari was low in coolant but that it drove faster than his truck, so low coolant must make cars go faster, and he was going to drain out some of the coolant in his truck so it could go as fast as the Ferrari. You would probaby suggest to compare the Ferrari's performance with low coolant to that same Ferrari with full collant. Noaks has no such controls in his paper, instead showing simply (and ONLY) that faster runners tend to drink less, like showing that Ferrari drivers don't take the time top off their coolant as much as truck drivers during a race. From his observation that faster runners drink less, Noaks concludes that losing coolant (dehydration) "during a marathon race may be ergogenic in those who drink according to the dictates of their thirst". This is saying that dehydration magically gives you energy (it is the low coolant that makes the Ferrari go faster) without providing any controled evidence or even any theory as to why that might be true. Low coolant (low hydration) lowers performance in controled studies of endurance athletes, backed up by the theory that fluids supply our bloodstream, which is (literally) our body's coolant and delivers oxygen to our muscles. His statement also assumes that athletes drink according to their thirst, but nowhere in the paper does it say that athletes were even ASKED whether or not they drank according to their thirst. Maybe faster runners simply ignore their thirst, pain, dizziness, cramping etc more than slower runners. It is well known that the harder we focus on something the less we notice everything else: the limbic system i.e. emotion center in brain regulates what sensory inputs make it through the thalamus to the sensory cortex.
These researchers are ready to drain the coolant from all our cars and the reviewers for the British Journal of Sports Medicine are happy to let them announce that fact as if it is a scientific conclusion. Noaks says that his results conflict with laboratory results, when they actually don't conflict with anything. This is a study of marathon hydration patterns, not of optimal hydration for performance. Nutrition is confusing enough when we use the scientific method. It gets confusing beyond usability when you don't. No wonder people feel like scientists go back and forth on the facts. Thank you to my friend Mike, a triathlete, who forwarded the the Wall Street Journal article on this paper (click then scroll down), which simply regurgitated the unsubstantiated interpretations of the researchers. So much for these scientists making their data usable to anyone, or the news media helping us filter through information so we can make better decisions in our lives.
I love science, but some make a bit silly discoveries that the public shouldnt know about coz it may be dengerous. Like some ppl live only on fruit diet I dont think its suitable for everyone. And you are right we have our own brains and should decide for our selves.
Posted by: Cindy | June 22, 2011 at 03:41 AM