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Changes in blood glucose and physical work capacity after heat dehydration Markon, Philippe Joseph Jacques


The purpose of this study was to examine the effects of a 4% lean body weight dehydration with two levels of rehydration for four hours on the changes in physical work capacity and blood glucose. Further, the study examined the effects on volume STPD, V02, R.Q. and true 02 during the physical work capacity test. A total of 7 university-aged males were involved in the experiment as subjects. Each subject was tested in two experimental conditions, i.e. 50% rehydration and 100% rehydration, on two separate days. Each set of tests consisted of blood samples drawn from the finger tip, a physical work capacity test with expiratory gas collection. Six sets of tests were distributed as follows: one at 6 A.M., and one half an hour after dehydration. The four other sets were hourly separated. The rehydration consisted of intake of tomato juice given after the set of tests 2, 3, 4 and 5. The amount given was equally subdivided and depended on the experimental condition. Analysis of variance indicated significant changes ever time for all dependent variables, except V02; significant changes between level of rehydration for weight, and significant changes for the level of rehydration by time interaction for true 02 and weight. There was no significant individual simple correlation coefficient between blood glucose and physical work capacity for each experimental condition. There was a mean decrease of 30% in physical work capacity after heat dehydration and only 40% of the loss was recovered without significant difference between experimental conditions. Gas exchange was also affected. The volume STPD increased after dehydration, true 02 decreased after dehydration and a better recovery showed up in the 50% rehydration condition. The R.Q. parameter, in fact, did not indicate significant changes but there was a slight decrease after dehydration. The level of blood glucose decreased after dehydration tut there was an increase in the middle of rehydration, even with the expected increase in blood volume, from the liquid intake. This suggested a very high level of gluconeogenesis on those last hours, probably due to glucocorticoid hormone action.

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