It’s that time of the month; Aunt Flow is visiting; the painters are in… however you phrase it, there’s no denying that periods can be a real inconvenience. This is particularly true if you’re a runner, but is it more than just the hassle of fitting tampons into your running belt? Can your period affect your running performance?
Most women have a 28-day menstrual cycle (anything from 20 to 45 days is normal). It’s divided into two halves. The first half is called the follicular phase, when you have your period and build up to ovulation. Day one is the day your period starts and ovulation (when the ovary releases an egg) occurs around day 14. Oestrogen levels gradually rise during the follicular phase. You then move into the second half, called the luteal phase, when the lining of the womb (endometrium) builds up preparing for pregnancy. Progesterone levels soar and body temperature increases. If the egg is not fertilized, progesterone and oestrogen levels fall rapidly, triggering the start of your bleeding and the cycle starts again.
Timing your training
Changing hormone levels alter your body’s metabolism and you might assume they alter athletic performance. Medical studies have not confirmed this. A study in 2011 found no difference in the heart rate, breathing, energy used or build up of lactic acid in a group of rowers at different times in their menstrual cycle. It’s a difficult area to study, as women vary so much in how their cycle affects them. Bigger studies involving other sports need to be done.
Those who notice cyclical changes in their running find their best training time is in the follicular phase, when oestrogen levels start low and gradually rise. Body temperature is lower and glycogen is broken down quickly, to release energy. This is a good time for shorter, high-intensity workouts and races. After ovulation, when progesterone levels rise, can be a hard time of the month for intensive training. Many women find they can perform endurance events well in this time, as oestrogen levels are still adequate and the body is better at burning fat for energy.
In the week before your period, you can feel bloated and sluggish, and your progesterone and oestrogen levels fall sharply. Your heart rate and breathing rate can also increase. You might not run at your best, but a gentle run will ease any premenstrual cramps and moodiness.
Running during your period
When Uta Pippig won the Boston marathon in 1996, she had blood pouring down her leg as she crossed the finish line. Her performance clearly wasn’t adversely affected by her period. However, if you have a very heavy flow it can leave you drained and lethargic. You may be anaemic and fewer red blood cells means slower transport of oxygen to your muscles. This can leave you short of breath and underperforming. You might feel faint and dizzy, too, so it’s not sensible to push yourself. There’s also the inconvenience of worrying about leaking and ruining your new running tights!
After the first couple of days, however, things change and, despite bleeding, it’s a great time to run for lots of women. Premenstrual bloating and lethargy have gone and your hormone levels are starting to rise again. Make the most of this early follicular phase and get some quality training and races done.
Make it work for you
Try keeping a diary for a few months. Note down the type of run you did, how hard you found it, your energy levels and mood, and see if there’s any pattern. You may be able to use your cycle to your advantage, planning high-intensity work when you know you perform best. Understanding why some runs just don’t feel good can stop frustration. Use your weakest time of the month to concentrate on core work, cross training and doing some enjoyable easy runs.
We’re all different. Some women hardly notice their periods; others find their lives are ruled by their cycle. Find what works for you, but the evidence is you can ‘go with the flow’.