That's one of the initial discoveries made by University of Adelaide PhD student Leanne Redman, who is studying the little-known impact of the menstrual cycle on women's exercise.
Early results of her research show that exercising at the later menstrual phase could burn more fat and help women to feel less tired.
"Results suggest that exercise performance is improved during the later part of the menstrual cycle-that is, when circulating concentrations of ovarian hormones (oestrogen and progesterone) are high," she says.
At the later menstrual phase, the hormones promote the use of fats as an energy source to support exercise. The use of fat in aerobic activity provides a more efficient delivery of energy, and results in fewer waste products being produced. These waste products normally contribute to fatigue.
Ms Redman's findings are of international interest to sport scientists and physicians involved in prescribing exercise programs to women for sport, fitness or health.
"According to our research, there would be clear benefits to women if their weight management programs, as well as providing a sound diet and lifestyle, took into account the physiological changes that occur during the menstrual cycle," she says.
Ms Redman is currently seeking women between the ages of 18-30 to volunteer for the last phase of her study.
This phase will look at the impact of synthetic hormones within the oral contraceptive pill on women's metabolism and exercise capacity.
The participants must be: non-smokers, already taking an oral contraceptive pill, exercise at least once a week, and from the Adelaide metropolitan area.
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Contact: David Ellis
david.ellis@adelaide.edu.au
61-8-8303-3173
Adelaide University
3-Jul-2002