Jessica Ennis-Hill is on a mission to close the gender data gap in health research. Her app, Jennis CycleMapping, is designed to help women understand their cycles and how to train during each different phase. Steph Eaves speaks to Ennis-Hill to find out exactly how it works

Tell us about Jennis. What is it?
On the surface it’s an app that uses a blend of tech and content to help women map their training to their menstrual cycles.

Lots of fitness programmes are shaped by male data, so we use the latest female physiological intelligence to help women tailor their workouts to what’s going on in their cycle. This means they get bigger training gains and work with their hormones, rather than against them.

But, really, Jennis is about us thinking much bigger. There is a huge gender data gap when it comes to women’s health, with just 8 per cent of studies exclusively featuring female participants. So, our big brand ambition is to close the gender data gap by doing our own research, then help women at every life stage understand their body and hormones better. We’re really excited about how we can make a difference in this space.

Where did the idea come from?
The original idea for Jennis came about after I was pregnant with my son Reggie. At the time, I was looking for quality advice on how to stay active through my pregnancy and looked out to the wider world for help. I was really shocked by how complicated and contradictory all the sources were.

I was lucky enough to have an elite team of physios and physiologists around me who could help. But the seed was sown. I knew that after I retired, I wanted to create a platform to help women get trusted advice about their hormones and physiology. At the time, I didn’t know what form that would take, but I knew I wanted to give women access to my network and the information and guidance I was lucky enough to have, to do what’s right for their bodies.

When did you launch? How has the app evolved and grown since then?
We launched back in 2019 and since then we’ve evolved on every level. Initially we were using agencies to help us plan and build, but we’ve taken everything in-house. It enables us to be so much more agile, and we’re testing and iterating much faster as a result. We also ended up rebuilding the app and changing the programming language it was built in – all stuff that I never ever thought I would need to think about when I was competing professionally.

Why is there still such a huge data gap in women’s health?
A woman as part of a clinical trial can be seen as too complicated, which is why we’re often left out of them. Men have a fairly simple daily rhythm of sex hormone fluctuation, where testosterone is highest in the morning and slowly declines over the day. This then repeats daily.

Women, in contrast, have a month-long ebb and flow of cycle hormones. The challenge here for health studies is that when you test a woman at one time in her cycle, she might not have the same response as she would have at another time in her cycle. This difference makes us expensive and complicated as trial participants. Because of this, lots of scientific studies leave women out.

What kind of experts are behind Jennis?
There are a whole team of experts across different fields – physios, physiologists, engineers, PTs. Plus, we reach out to lots of other experts for our body literacy content – sleep experts, hormonal nutritionists, psychologists etc.

Tell us about the new CycleMapping programme – how does it work?
When you sign up, you go through a quick questionnaire, which helps us understand your fitness goals, cycle length, period and pre-menstrual symptoms and your fitness level.

From here, we’ll be able to pinpoint where you are in your cycle and make training recommendations based on the hormone profile of the phase that you’re in. Each day you’ll then be served a new selection of workouts, plus daily insights that help you work with your hormones at that point in your cycle.

Can you tell us a bit about the research behind CycleMapping?
From a Jennis point of view, we worked very closely with physiologist Dr Emma Ross. She used to be head of physiology at the EIS (English Institute of Sport) and has been working in this field for decades.

From her input and the studies she shared, plus our own tests with Beta users, we created the CycleMapping programme.

In terms of results, there are lots of studies that show how training in this way can reduce negative cycle symptoms and build lean muscle more effectively – and from our own Beta testers we are getting lots of interesting results around reduction in period symptoms; higher motivation to train and weight loss experienced by women, but these are all very early anecdotes.

Do you use CycleMapping in your training?
Yes, I have been CycleMapping and was one of the early testers of Jennis CM and I have found it really helps me understand my moods a lot more – I can tune into the way I feel alongside the four phases of my cycle, and then train or rest accordingly.

I have found too that when I am premenstrual I recognise this more now and actually listen to what my body wants instead of trying to push through the symptoms. As an athlete I thought I was in tune with my body but pregnancy and now CycleMapping has really improved my own body literacy.

What key features are included in the app?
I think the onboarding questionnaire is really important, as that helps us personalise the plan each user gets. The feedback functionality is also really crucial. By interacting with that, we can tweak people’s plans – shifting the sessions if their cycles change, reacting to changes in symptoms and so on.

What are your future plans for Jennis?
To be honest it’s really hard to predict. There are definitely areas that I would like us to move into, but we’re very much going to be led by our consumers and what they want.

To be one of the first to try Jennis CycleMapping, visit cyclemapping.jennisfitness.com to register. (Apple and Android versions both £14.99 per month).