Advice about syncing exercise to menstrual cycles is all over social media. Does it work?

Cycle syncing helps Simone Saunders feel prepared.

The practice of tracking each phase of the menstrual cycle is being promoted online as a way to optimize personal exercise and lifestyle regimes.

Saunders, a registered social worker, uses it to inform her choices around exercise, wellness and work by knowing the symptoms she's come to expect during her cycle.

Whether that's scheduling in more rest during her luteal phase, or reducing her in-person workload when she knows her period is coming, it's become part of building her monthly routine.

"In paying attention to that for myself, I noticed that it allowed me to plan my life a lot better," said Saunders.

The menstrual cycle's effect on exercise is getting attention in the professional sports world, too. In April, soccer governing body FIFA announced funding for a new study that looks at the menstrual cycle and ACL injuries within women's football.

A 2023 research review from the University of Vigo in Pontevedra, Spain, has found that a female athlete's hormonal changes could lead to potential injuries by altering biomechanics and movement patterns. The research also indicates that female athletes have a harder time balancing, or building and rebuilding muscle tissue, when hormones like estrogen and progesterone increase in the body.

But clinicians say there isn't sufficient evidence to support blanket advice for cycle syncing, or phase-based training.

They say getting to know your own menstrual cycle, and what you can expect from each phase, can have benefits, however.

As a former professional golfer, women's health researcher Kelly McNulty says that the "female factor" wasn't being considered in training. This was the start of an interest that continued into her research.

With a PhD in female exercise physiology, and a range of research interests in optimizing female health and performance, the menstrual cycle is a topic McNulty knows well.

Despite growing public interest in cycle syncing, she cautions against making major changes based on the practice.

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"It is a bit of a trendy thing," said McNulty, a post-doctoral researcher at Northumbria University and Bangor University in the U.K.

"There's no real blanket guideline for all women to say train this at X phase, or train this at Y phase."

The individuality of every person's body and cycle makes broad recommendations difficult, and adding hormonal contraceptives into the mix makes things even more complicated to generalise, she explained.

Though McNulty's research found that performance was slightly reduced during the early follicular phase, she emphasized that certain types of training shouldn't be limited to specific times of the cycle.

"We know that women and girls are chronically undertrained, particularly strength training," she said.

McNulty says that strength training can be valuable at any stage of the cycle, and limiting yourself in the absence of effective data isn't necessary.

Tracking can help identify clusters of symptoms that may be affecting exercise, but that it shouldn't rule your life.

Tracking for roughly three cycles is a good start for noticing patterns, she said.

"Gold medals are won at any phase of the menstrual cycle. So it's just remembering that as well, because some people might be affected and some people might not," she said.

More research is underway, but results take time, she added.

Physiotherapist Uma Ghosh says, despite the lack of evidence, there are pros to knowing your body better.

"You can tune into how you feel, and adapt your workouts to however you feel," said Ghosh, who is also an adjunct lecturer at the University of Toronto, in an interview with Day 6.

Ghosh emphasized that knowing how you feel at different phases in your cycle can help take some pressure off of expectations and performance for the average gym-goer. She says to "not be so hard on yourself."

"The more you know, the better you can determine when things are not working well, or what you can present to your doctor if you have to go and see them," said Ghosh.

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She recommends tracking everything — not just the first day of your bleed.

"Document how you feel mood-wise, and your energy, and your sleep quality, and your bowel movements, your bladder health, your mental health," she said.

"When something's not right, you pick it up super quick."

Though cycle syncing's popularity might not be backed by science, it's an active conversation around menstrual health that McNulty says is far from over.

"We don't want to stop people talking about it, but we also want to make sure people are getting the right information. It's getting that balance."

Saunders has been candid about her menstrual phases online, sharing videos about her experience. She says the reaction has been positive.

She says she's received direct messages from people that have started to take a closer look at their own cycles after seeing her content.

The practice has also helped people understand the symptoms of their partners' cycles better too, Saunders added.

"I think that that's just generally helpful not only for people's day-to-day lives, but understanding the people around them as well."