Effect of hydration state on resistance exercise-induced endocrine markers of anabolism, catabolism, and metabolism.

Hypohydration (decreased total body water) exacerbates the catabolic hormonal response to endurance exercise with unclear effects on anabolic hormones. Limited research exists that evaluates the effect of hypohydration on endocrine responses to resistance exercise; this work merits attention as the acute postexercise hormonal environment potently modulates resistance training adaptations.

The purpose of this study was to examine the effect of hydration state on the endocrine and metabolic responses to resistance exercise. Seven healthy resistance-trained men (age = 23 ± 4 yr, body mass = 87.8 ± 6.8 kg, body fat = 11.5 ± 5.2%) completed three identical resistance exercise bouts in different hydration states: euhydrated (EU), hypohydrated by ∼-2.5% body mass (HY25), and hypohydrated by ∼5.0% body mass (HY50). Investigators manipulated hydration status via controlled water deprivation and exercise-heat stress. Cortisol, epinephrine, norepinephrine, testosterone, growth hormone, insulin-like growth factor-I, insulin, glucose, lactate, glycerol, and free fatty acids were measured during euhydrated rest, immediately preceding resistance exercise, immediately postexercise, and during 60 mm of recovery. Body mass decreased 0.2 ± 0.4, 2.4 ± 0.4, and 4.8 ± 0.4% during EU, HY25, and HY50, respectively, supported by humoral and urinary changes that clearly indicated subjects achieved three distinct hydration states.

Hypohydration significantly 1) increased circulating concentrations of cortisol and norepinephrine, 2) attenuated the testosterone response to exercise, and 3) altered carbohydrate and lipid metabolism. These results suggest that hypohydration can modify the hormonal and metabolic response to resistance exercise, influencing the postexercise circulatory milieu.

Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, Connecticut; 2 Department of Kinesiology, California State University-Fullerton, Fullerton, California

Journal of Applied Physiology Sep2008, Vol. 105 Issue 3, p816 9p.

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Basic stuff but interesting none the less

If Im reading this right they dehydrated a group rather than over hydrated and therefore this proves very little

They had trained athletes start resistance exercise either hydrated, dehydrated by 2.5% body mass or dehydrated by 5% body mass.

What they are saying mate is if you begin some form of resistance exercise already dehydrated (quite possible in summer, warmer climates or if your very active or training first thing), then this may:

-increase cortisol & norepinepherine
-slow the rate at which testosterone responds to resistance exercise (building muscle)
-alter CHO and fat metabolism

Take home message is make an effort to drink more water to make sure you are in a normal hydration state in order to maintain optimal hormonal responses. Of course other factors come into play here but this is just looking at one peice of the puzzle.