A woman points to a colour-coded grid dividing the menstrual cycle into four phases, each paired with a different list of exercises. "When you're bleeding, you want to be doing steady-pace jogging, Pilates, barre, walking, resting," she tells viewers. This is one of thousands of videos on TikTok and Instagram suggesting that people change their workouts depending on where they are in their menstrual cycles - something known as 'cycle-syncing'.
So-called cycle-syncing workout plans have surged in popularity online, with Google searches for the term rising 740% since 2022 and more than 55,000 TikTok videos now using the #cyclesyncing hashtag. Most of the advice is shared by fitness and wellness creators rather than medical or research experts. They divide the menstrual cycle into phases, recommending: gradually increasing intensity in the follicular phase leading up to ovulation harder strength or high-intensity training around ovulation easing off again during the luteal phase (between ovulation and the start of your period) Kelly McNulty, a researcher at Leeds Beckett University specialising in menstrual cycles and exercise, says there is evidence that some women experience changes in symptoms, energy or perceived strength across their cycle.
But that is different from evidence that all women should train in a particular way at a particular point, she tells the BBC, adding that these videos are "a trend based on marketing rather than any kind of research or evidence". "There isn't any research to support that kind of phase-based prescription," she says. A key issue is that menstrual cycles are highly individual, McNulty adds - they can differ between women, and one woman's experience can also change from one cycle to the next.
That makes the blanket advice often found on social media difficult to apply, she explains. Many cycle-tracking apps and programmes are also designed around relatively regular menstrual cycles that are 21 to 35 days, which can make their recommendations less applicable to people with irregular periods, or those using hormonal contraception. "It's not so much about doing certain exercises in certain phases, it's about working with your own individual body and what your needs might be." Cesci Burgoyne, a nurse based in Sydney, Australia who is also a qualified personal trainer and nutritionist, adjusts her training depending on how she feels in her cycle.
She doesn't follow a prescriptive plan, she says, but instead makes changes intuitively. "In my luteal phase I'll try and ease off in the training," she tells the BBC. "In my follicular phase, I'm so energised, I feel like I can lift so much heavier.
I like to try and get my long runs in." Burgoyne also welcomes the growing attention on women's health, and says that exercise and nutrition research has historically focused heavily on male bodies, with findings then often applied to women. Fitness creator Sarah Mackay, known as @liftwsarah on Instagram and TikTok, has also noticed her energy, motivation, cramps and mood change through the month. But she deliberately avoids strict plans because, she says, "there are too many variables at play".
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