Do you regularly experience tender or painful breasts? Are you convinced that your boobs grow across your cycle? Then here’s the cycle science behind it…
Sore boobs are a big deal, with millions of women experiencing them every single month.
To give you an idea of numbers, 68% of women aged 18-44 regularly experience low-level breast soreness before their periods, with the discomfort lasting for between 1-4 days a month, according to a US study . Then, there are a further 20% of women who report moderate-to-severe breast pain that lasts at least 5 days every month.
Add it all together and that’s at least 24-sore-boob days every year for millions of women. And yet, we hardly ever talk about it. So, just what’s going on, what you can do to ease the discomfort and can exercise help? We turn to Jennis physiologist Dr Emma Ross to find out.
What triggers the breast pain?
“Just like your brain, your breast tissue has receptors for oestrogen and progesterone,” says Jennis Physiologist, Dr Emma Ross. “When these hormones rise and fall across your menstrual cycle (see graph below), they can influence the size and sensitivity of your breasts, with some women’s breast volume changing by an incredible 40% across a single cycle.”
Can your breasts really grow that much?
Yes, really! According to a 2018 study your boobs start to grow after ovulation and continue to grow right up until the end of your period, which is when your boobs are at their biggest.
The growth happens because oestrogen causes the breast ducts to swell, which can affect your breast volume. “For most women, there’s an average of 14% difference in the size of their boobs across their cycle,” reveals Dr Emma. “But for some women in the above study, their breasts grew by 40%!”
At what point in the menstrual cycle does breast pain start?
For most women, boob soreness - or 'cyclical mastalgia’ as it’s called in the medical profession - “occurs when oestrogen and progesterone rise in the Luteal phase, and can continue into the Pre-menstrual Phase,” says Emma.
When it comes to what’s causing the soreness, we know that hormone levels are to blame, but there are a few theories about exactly what's happening.
“One possible theory is that when oestrogen and progesterone rise during the Luteal Phase (see graph below), the breast milk ducts can become swollen and it’s this that causes the discomfort,” says Emma.
Another theory focuses on the rise in progesterone and suggests that an excess of progesterone can impede the cell receptors that balance levels of fluids and salts in your body, which in turn leads to bloating from fluid retention, plus boob soreness.”
Whatever the cause, the good news is that there are foodie, physical and practical things you can do to ease the ache.
Can you eat to beat boob soreness?
A 2019 review found that flaxseed and foods rich in vitamin E, such as nuts, seeds and avocado, may help to reduce the breast soreness associated with the menstrual cycle, reducing both the severity and duration of cyclic mastalgia.
For general breast health and a reduction in breast discomfort, iodine, found in seafood and seaweed is believed to be really helpful. “This essential trace mineral is really crucial for healthy breasts because it stimulates a key oestrogen receptor in the breast tissue, ” says Emma. “This stimulation encourages oestrogen to bind to it and leads to healthy breast cell development.”
Exercising can help to reduce breast pain by boosting blood flow around the body, while releasing endorphins which act as natural painkillers.
If you needed an excuse to eat oysters this weekend, how about this? Just three ounces of cooked oysters can provide up to 93 mcg of iodine , nearly two-thirds of what you need per day.
Finally, for supplements, the same review found that evening primrose oil may be beneficial, something also echoed amongst the Jennis community.
Would a better-fitting bra help?
“I really recommend going for a proper sports bra fitting, as supportive bras and sports bras can ease breast pain by reducing movement of breast tissue,” says Emma.
“With 80% of us wearing ill-fitting bras and between 20 and 40% of active women reporting that breast pain interferes with their ability to train, getting properly fitted for a sports bra can help overall breast and back health, while also minimising pain and discomfort in the breast during exercise.”
How should I adapt my exercise to help with sore boobs?
Although it may feel counterintuitive to start jumping around when your breasts are sore, a 2019 study found that exercising can help to reduce breast pain by boosting blood flow around the body, while releasing endorphins which act as natural painkillers. Exercise also helps balance oestrogen and progesterone levels, which are thought to be behind cyclic mastalgia.
Even if you don’t feel up to vigorous exercise (and that’s totally fine), gentle upper body moves can increase blood flow to the pectoral muscles that connect the chest area to the upper arms. A Jennis yoga flow is always a good choice for stretching out the arms, neck and upper body muscles, while an upper body and core HIIT workout is just the thing if you have more energy in the tank.
When to see your GP for breast pain
Not sure if your breast pain is caused by your menstrual cycle? Then it’s worth logging the dates of your pain and period for two months. If it’s cyclic mastalgia (menstrual-cycle-related-symptoms), you’ll probably notice a pattern in terms of when you experience the soreness and for how long. I
If you don’t see a pattern, the pain is difficult to manage or you have other symptoms, such as a lump, nipple discharge or dimpled breast skin, book an urgent appointment with your GP or call 111. Find out more about breast pain.
Check out the Jennis CycleMapping app for daily workouts and advice that’s synced to your menstrual cycle