Exercise and menstruation have a complex relationship, with various elements affecting just how often (or not) you have a period. The ideal is to achieve the middle ground: not too much and not too little exercise. A bonus is that exercise, in moderation, is believed to help relieve menstrual cramps.
An Australian study showed that exercising after ovulation - at the midpoint of the menstrual cycle - is easier, and burns more fat than exercising in the first week of the menstrual cycle.
The researcher examined the effect of exercise on a group of young, healthy women with normal menstrual cycles. In the first week after menstrual bleeding began, the women were given two exercises to do, and repeated them in the week after they ovulated. These times were chosen because the levels of the hormones oestrogen and progesterone increase toward the end of the menstrual cycle.
The study found that the women burned more fat for the same amount of exercise in the second half of the menstrual cycle, and that these women perceived the exercise and their recovery from it quite differently from those exercising in the first half of the cycle.
"Women will often come in and say they feel tired and sluggish and headachy at the beginning of the month," said Leanne Redman, a PhD student at the University of Adelaide's Exercise Physiology Laboratory. "On those days when they're not performing as well, even though they're achieving the same level, they're finding the exercise a lot harder."
She found that at the beginning of the month, when both oestrogen and progesterone are low, performance is not as good. "In the second half of the cycle, when both hormones are high, that's when we're getting an increase in fat metabolism," Redman concluded.
Too much exercise
Too much exercise can cause dramatic irregularity in periods or a total absence of them known as secondary or exercise-associated amenorrhea (EAA). There are various reasons for this such as loss of body fat. The body may also be "tricked" into perceiving the very heavy exercise as an abnormality, causing it to stop a menstrual cycle entirely.
A "protection factor" kicks in to guard the body against pregnancy during this time of physiological stress.
An added issue is that the glands secrete adrenaline but, because the body is not actually in danger, this overproduction of adrenaline causes more problems affecting the menstrual cycle, too. All these adverse reactions may eventually cause a uterus to "tip" or become permanently scarred.
EAA may also cause loss of bone density. Researchers in the US found significantly lower bone density in female runners with amenorrhea. The discovery of this bone loss was a surprise to the medical community because one of the benefits of weight-bearing exercise is an increase in bone density.
Too little exercise
We all know that the less we do, the less we can do. And yes, even your body systems can slow down if you do not exercise enough. A serious lack of movement can cause muscles to atrophy which can affect the menstrual cycle.
Enough exercise strengthens our system. Too little can cause or contribute to severe cramping or dysmenorrhoea.
What to wear
Tampons: there is a wide variety of tampons available. They come in different sizes (mini to super-plus). Some have applicators and some have none. They are ideal for exercise and are less visible than pads. Some women with heavy flow use a panty liner or sanitary pad as well, for extra protection.
Sanitary pads: This is a good option for young women who have just started menstruating. You get maxi pads for heavy flow or night use and mini for light days. Most of them have a stick-on strip to secure to your panties. They can move around during heavy exercise and are not ideal for swimming as theyabsorb water and can potentially leak.
Menstrual cup: although these have been around a long time they are relatively new to a lot of women. Made out of silicone rubber they are inserted into the vagina and form a seal against the "wall" preventing leakage. It may take a bit of adjusting to perfect the fit, but they are also good for use during exercise.
- (Updated by Robyn von Geusau, Health24, February 2011)