Doctors and scientists are increasingly concerned about the high prevalence of menstrual dysfunction among female athletes. For it is now clear that reduced levels of reproductive hormones pose a significant threat to bone health, increasing the risk of sport-related injuries and osteoporosis.

And that’s not the end of it: US nutritionist Prof Melinda Manore claims it’s not uncommon for female athletes with menstrual dysfunction to complain of fatigue, frequent injuries, irritability and poor athletic performance, with a consequent increase in psychological and emotional stress.

Furthermore, ‘the long-term effects of diminished reproductive hormones, especially oestrogen, on other body systems (eg cardiovascular health, cognitive function, immune function) have not yet been clearly established’.

Prof Manore points out that a number of factors may contribute to the development of athletic menstrual dysfunction, including energy balance, exercise intensity and training practices, body weight and composition, disordered eating behaviour, physical and emotional stress and individual susceptibility.

But the most important trigger for menstrual problems, ranging from irregular periods to completely absent ones, appears to be ‘energy drain’ or ‘negative energy balance’ – in other words failing to match energy expenditure with adequate food intake. For obvious reasons, this is a particular problem for athletes in aesthetic or ‘lean-build’ sports, such as dancers, runners, gymnasts and figure skaters, who report the highest incidences of menstrual dysfunction and frequently use long-term dieting to maintain a competitive weight.

Improving an athlete’s overall energy balance can go a long way towards reversing diet-induced menstrual problems, says Manore. This may means increasing energy intake (ideally by small increments of 200-300 kcal/day) while simultaneously reducing exercise energy expenditure – eg by adding a rest day to the weekly routine.

So what is a reasonable intake? According to Manore, on anything less than 1800 kcal/day ‘it is almost impossible to get adequate macro- and micro-nutrients to maintain good health and have the energy to fuel an intense training programme’. Most female athletes require at least 2,300-2,500 kcal/day to maintain body weight, and those involved in endurance sports like the marathon or triathlon may need as many as 4,000.

Female athletes are particularly likely to be low in protein (especially vegetarians), carbohydrate, essential fatty acids, pyridoxine, riboflavin, folate, calcium, magnesium, iron and zinc, and may need supplements to achieve adequate intakes. Because those with menstrual irregularities face risks to bone, intakes of bone-building nutrients need to be carefully monitored for adequacy, and supplementation may be necessary, particularly if dairy products are not used.

Females athletes seeking to avoid the range of problems that accompany negative energy balance leading to menstrual dysfunction are offered a range of helpful strategies, including the following:

Less focus on the scales and more on healthy habits, making good food choices and eating regular meals and snacks;
Don’t constantly deprive yourself of favourite foods or set unrealistic dietary rules – remember that all foods can fit into a healthy lifestyle;
Don’t skip meals or let yourself get too hungry;
Consume fluids throughout the day – don’t use dehydration as a means of reaching your goal weight;
Always eat something for breakfast – it will stop you overeating at lunch;
Use a multivitamin and mineral supplement in preference to single nutrient supplements unless otherwise recommended by a health professional.
Sports Med 2002;32(14)p887-901

Isabel Walker