A study found that women with larger cup sizes seem to be more susceptible, but childless women also seem to be more prone and wearing a sports bra doesn't always help. The study got published as London geared up for its annual international marathon.
The authors base their findings on the responses of just under 1300 female competitors passing through the registration zone for last year's marathon in the capital.
The women were asked how much exercise they took, and its intensity - including participation in marathons - whether they wore sports bras and/or other support, and if they suffered breast pain.
Almost one in three (32%; 412) of the runners said they experienced breast pain, a proportion that rose with increasing cup size: half of those with a cup size of F or larger complained of pain compared with 1 in 4 of those with an A size cup.
But childless women were also significantly more likely to say they had breast pain than women who had given birth.
Half blamed their breast pain on the menstrual cycle, but almost a third (30%) said it was only sometimes associated with this. And while around 1 in 8 (12%) women said that hormonal factors worsened their breast pain, 1 in 7 said that exercise made their symptoms worse.
Almost 1 in 10 (8%) described their pain as distressing or excruciating. And 1 in 6 (17%) said their symptoms affected their ability to exercise.
The most popular way of relieving symptoms was to wear a sports bra, with 1 in 5 respondents citing this option. But 9 out of 10 of all participants said they wore a sports bra while running.
"[This suggests] that sports bra use is not necessarily perceived as a method to treat mastalgia and that sports bra design and manufacture needs improvement," say the authors.
Around 1 in 8 of those with breast pain opted for painkillers or holding their breasts while running. But almost half (44%) just put up with their symptoms and did nothing to alleviate them, the responses showed.
"The link between exercise and [breast pain] has yet to be established," conclude the authors. "However, this study identified that exercise was the most prevalent factor in mastalgia occurrence, which may have implications for its management," they suggest