Research to Reader: fertility science
During your typical menstrual cycle you experience fluctuations in oestrogen and progesterone along with follicle stimulating hormone (FSH) and luteinizing hormone (LH) that influence when, and if, you ovulate. In a number of women, menstrual periods are absent while others, particularly the 10% of women with PCOS, experience infrequent or irregular periods. Exercise can be a modulator of the menstrual cycle helping maintain normal ovulation in healthy active women (1), and restoring normal menstrual function (and fertility) in overweight women (2). To understand the role of exercise let’s first take a look at energy balance.
Underweight or Extreme Exercise
Energy balance is the relationship between how much energy you expend through exercise, activities of daily living and your basal metabolic rate (the energy we need to keep our basic bodily functions going), and how much energy you take in from food and drink. For women that have a low body mass index and low body fat levels, engaging in excessive exercise is likely to lead to a negative energy balance unless particular attention is given to ensuring adequate nutrition. Women with a low body mass index participating in more than 30 minutes per day of moderate or vigorous exercise are at greater risk of anovulation (and hence infertility) (1). Even in normal weight women with no tubal defects and that had never been pregnant, engaging in extremely heavy / vigorous exercise for more than 60 minutes a day increased the risk of ovulatory infertility by 600% (3)! While ensuring you are getting enough nutrients for the amount of activity you are doing is important, so is getting the balance of moderate and vigorous exercise right. It is imperative that your body composition and current activity are considered to prescribe the right amount and intensity of exercise to optimise your menstrual cycle and ovulation.
Overweight and Sedentary
Just as being underweight may impair hormones that influence ovulation, being overweight (body mass index greater than 25) and not engaging in sufficient activity is also associated disturbances of the menstrual cycle, increasing the risk of infertility. The good news is that the right exercise prescription can restore balance to the menstrual cycle. A six month exercise intervention in overweight women with a prolonged history of not ovulating (with and without polycystic ovary syndrome) restored ovulation in 89% of women (2) and 77% became pregnant (4). As exercise had restored ovulation, 27% of these pregnancies happened spontaneously without fertility treatment. What a cost saver! For infertile overweight women, exercise should always be considered as a first option.
How do you Restore Balance?
The benefits of exercise for increasing fertility are numerous and one of these is regulating the menstrual cycle for normal ovulation. If you are sedentary or do not participate in regular physical activity, undertaking too much exercise too soon can be detrimental to your menstrual cycle (5). A gradual progression in your exercise prescription on the other hand is most beneficial for restoring hormonal balance and regular ovulation.
If you have experienced irregular menstrual cycles and this is the primary source of your infertility then the right exercise prescription could increase your chances of spontaneous conception. The right balance starts with the right exercise prescription – your custom exercise program from the ivf project!
1. Chavarro JE, Rich-Edwards JW, Rosner BA, Willett WC. Diet and lifestyle in the prevention of ovulatory disorder infertility. Obstetrics and gynecology. 2007; 110: 1050-8.
2. Clark AM, Ledger W, Galletly C, Tomlinson L, Blaney F, Wang X, et al. Weight loss results in significant improvement in pregnancy and ovulation rates in anovulatory obese women. Human reproduction (Oxford, England). 1995; 10: 2705-12.
3. Green B, Daling J, Weiss N, Liff J, Koepsell T. Exercise as a risk factor for infertility with ovulatory dysfunction. American Journal of Public Health. 1986; 76: 1432-6.
4. Clark AM, Thornley B, Tomlinson L, Galletley C, Norman RJ. Weight loss in obese infertile women results in improvement in reproductive outcome for all forms of fertility treatment. Human reproduction (Oxford, England). 1998; 13: 1502-5.
5. Bullen BA, Skrinar GS, Beitins IZ, von Mering G, Turnbull BA, McArthur JW. Induction of menstrual disorders by strenuous exercise in untrained women. N Engl J Med. 1985; 312: 1349-53.