In a recent study 54% of women say they stopped exercising around their menstrual cycle. Yet for many women there is no reason to stop exercise during the cycle (Kate Carter - Running World - 2019).
The decline of hormones in the premenstrual period causes an inflammatory reaction, which can impair mood, sleep, energy levels, and recovery, according to what we know about the cycle and performance. When the period arrives, hormone levels begin to rise, and energy levels recover.
A study conducted “The effect of the menstrual cycle on running economy” found that in the mid-luteal phase caused an increase in core temperature and minute ventilation (volume of air breathed in and out per minute) due to the hormone progesterone. At exercise intensities that are relevant to training and performance, running economy was hindered. This reduction in running economy may have a major influence on training and performance in physiologically demanding environments.” (Esther Goldsmith, 2020, St Mary's University).
This means that in the mid-luteal phase women may find it hard to run at a regulated body temperature in hot conditions and to maintain control of their breathing. Cooling strategies like soaking clothing in cold water, such as headbands, arm sleeves and bandanas will help in trying to cool the body down, however we are fighting against an increased metabolic rate at this stage of the cycle, bear in mind intensities and time frames in running will impact this. This is why it would be beneficial for women to plan their running around their cycles in order to understand why at certain stages they may feel a certain way or not be able to perform to a usual level.
Overall you don’t need to let these symptoms dictate your training, as long as you adjust fueling and body temperature accordingly then exercise itself can help alleviate period pain. Low-moderate intensity aerobic exercise like running can reduce bloating (extra water
retention) which increases blood circulation and the release of “feel good hormones” called endorphins.