For many women, it is the time of the month when little seems more appealing than curling up with a hot water bottle.
But new evidence suggests that going for a walk or run could dramatically reduce period pain compared with staying on the sofa.
It could even reduce pre-menstrual tension symptoms, like tearfulness and irritability, which is a more unexpected finding.
A scientific review led by University College London combined data from 82 separate studies examining period symptoms and how physical activity may affect them, involving more than 100,000 women around the world.
Compared with women who did a medium or high amount of physical activity, less active people had a 67 per cent higher risk of suffering menstrual pain.
They had a 22 per cent higher risk of pre-menstrual syndrome (PMS), also known as pre-menstrual tension (PMT), which is a set of physical and emotional changes caused by fluctuating hormones before a period arrives, including mood swings, irritability, headaches, spots and bloating.
Women who did not exercise were 67 per cent more likely to report menstrual pain
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What causes pre-menstrual tension?
Painful periods are caused by the womb squeezing as it sheds its lining, which cuts off its blood supply and triggers the release of pain-causing chemicals called prostaglandins.
Exercise may counteract this process by releasing pain-reducing anti-inflammatory proteins into the body.
Being active may help with symptoms of PMT, such as bad moods and emotional reactions, through the feel-good endorphins exercise releases.
• Call for action as 235,000 women suffer severe PMT every month
But it could also just help to reduce women’s stress, boost their mood and provide a pleasant distraction.
Dr Jo Blodgett, senior author of the scientific review, from University College London’s Institute of Sport, Exercise and Health, said: “Physical activity is low-cost, easy for many and a promising way to manage period pain and PMS.
“Women and girls need solutions, rather than just enduring these symptoms, which have long been neglected in healthcare and scientific research.
“Ours is the first review of real-world studies looking at women’s daily physical activity and menstrual symptoms.
“There are limitations to the studies we analysed, for example women mostly self-reporting their physical activity level instead of it being measured by a device, but we found strong evidence that women who did either no or low levels of physical activity had higher odds of having menstrual pain and PMS.”
What type of exercise is best for PMS?
The review, published in the Journal of Women’s Health, mainly looked at studies investigating the link between leisure-time physical activity, such as exercise or sports, and menstrual symptoms.
But some studies also analysed other types of physical activity, like people walking or cycling to work, having active jobs or being active when they did housework.
One of the studies, looking at more than 7,000 women in Taiwan, found those who got regular exercise at least once a week were about half as likely to have PMT-related crying episodes, compared with women who did no physical activity.
They were 25 per cent less likely to report suffering from a low mood before their periods, and 22 per cent less likely to say they had struggled with feeling irritable.
There was some slight evidence to suggest that lower physical activity was also linked to irregular periods.
But the researchers want more and better evidence, so are looking at how they can use data on people’s physical activity levels, recorded by devices like smartwatches, to understand the amount and type of movement which may reduce difficult period symptoms.
They will also investigate how sleep and sedentary behaviour affects things like period pain, PMT and menstrual cycle length.
Lucy Buchanan-Smith, first author of the study from UCL, said: “Encouraging an active lifestyle could empower women, offering a simple, low-cost and accessible way to manage menstrual health.
“The findings from our review are consistent with what we’ve seen in six to eight-week exercise studies, suggesting that even small increases in physical activity such as walking and cycling, may reduce painful menstrual symptoms.”