Clark, Sally A (1996) The effects of oestradiol administration on energy metabolism during prolonged exercise in amenorrheic athletes. Research Master thesis, Victoria University of Technology.

Abstract

To delay the onset of fatigue in endurance exercise it is advantageous to prolong muscle glycogen depletion. Oestradiol (the female sex hormone) has been shown to increase muscle glycogen content at rest and increase the availability of fats as a fuel source during exercise therefore delaying the onset of fatigue. The effects of oestradiol administration on energy metabolism during sub-maximal exercise were examined by administering oestradiol using a transdermal oestradiol therapy system in five amenorrheic athletes. The subjects completed two exercise trials for a period of two hours. Prior to each exercise trial they underwent three weeks of either an oestradiol or a placebo treatment. A three-week washout period elapsed before the other treatment was administered. In all trials heart rates and perceived exertion were monitored, respiratory gases were collected, blood samples were taken from a vein in the antecubital space and analysed for metabolites and hormones. Pre and post exercise muscle biopsies were taken in two subjects and were analysed for glycogen and lactate. Results from this study suggest that moderate elevation of semm oestradiol concentrations in amenorrheic athletes has no effect on substrate utilisation during two hours of sub-maximal exercise. There were no significant differences in heart rates, perceived exertion or respiratory exchange ratios, blood and plasma metabolites including glucose, lactate and free fatty acids; or plasma insulin, Cortisol and catecholamines. It therefore appears that raising oestradiol concentrations to those achieved in the present study is not advantageous for an amenorrheic athlete during two hours of sub-maximal exercise.

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