It’s 8.30am on a Wednesday morning and Pip Black and Joan Murphy have spent the last hour bouncing around outside Kings Cross, leading 350 people (mainly women) in a Nike X train class. It’s part of a new collaboration between the fitness brand and their company, Frame, an exercise studio that launched just over seven years ago and redefined the idea of working out in London.

Running classes such as ‘80s aerobics and music video, Frame brings an element of fun and excitement to the ever-expanding fitness market. Rather than simply go to a class and workout, Black & Murphy wanted to create a lifestyle brand, to turn exercise into an event.

“We were going to the gym and just found it boring,” says Murphy. “You’d say to someone, ‘what are you doing tonight?’ and they were off to play five-a-side football. You’d know they were off to have a good time and then go to the pub with their mates afterwards. But if you said to someone, ‘I’m going to the gym’ they’d be like, ‘oh. Running on the treadmill. Fun’.”

“We wanted something that would appeal to women,” adds Black, “but also to people who were into fashion or music. We definitely didn’t want to always be talking about weightloss or pain or negative things, we wanted our voice to be how you’d talk to a friend - quite casual, tongue in cheek”.

After they’d had the idea they did a bit of market research and then set about working out their business plan. Both had a business degree and a background in sport but neither had worked in the fitness industry, they just knew that as consumers of it, they weren’t happy with the current options available. When they’d finally put together the business plan, a mere 62-pages pages long, they took it to the bank. Scraping in just before the crunch they found getting investment easier than expected.

“Back then the business world was quite male dominated,” says Black. “But rather than going in and worrying about it, we were competitive about it. Knowing that gave us a bit of a fire in our bellies, we were like ‘right, we’re going to go and show these middle-aged men at the bank what’s what’... we almost saw it as a positive.”

Rather than aping the fitness industry as it then stood, Black & Murphy set out to redefine it by getting rid of all the things they didn’t like. Despite pressure from bankers and industry commentators, they resisted a purely subscription model instead offering classes on a pay as you go basis.

They also want to move fitness away from something you do in order to look a certain way and into something you do for the sheer joy.

“[The fitness industry] is an industry built on people’s insecurities,” says Murphy. “There are a lot of things you can do to make someone feel bad to make them want your product. We’re really passionate about the fact that this is about lifestyle ... Everything we do we try to make it positive, so we don’t brandish transformation photos around, we don’t talk about ‘you’re going to burn lots of calories in this class’ ... We try and keep it in a positive light, whereas the industry probably plays on insecurities.”

As first time entrepreneurs they’ve had to learn a lot on the job, particularly when it comes to disrupting an industry that had run on the same model for decades. Opening took longer than expected because they wanted an online booking system. What is standard now didn’t exist seven years ago, so they ended up building one from scratch.

“We’ve spent a lot of money building things because we’ve been ahead of our time,” says Murphy.

But this constant strive to be better helped them stand out from the crowd. When I ask them whether they think they’re a success, Murphy responds with “we’re a work in progress”, while Black says that they’re never quite satisfied.

“Joan and I are always trying to make things better. Nothing is ever perfect, it can always be improved on and there’s so many things that we need to do. If you saw our to-do list at the moment ... every day we tick something else off but by the time you’ve done that something else has come up.”

They’ve grown organically over the past seven years, starting with one studio in Shoreditch (“when we first opened we didn’t bother running classes on a Sunday, we knew everyone would be too trashed” - Murphy), they now have two London sites and a third opening in Kings Cross in October. This growth doesn’t mean they’ve abandoned the scrappy, start-up mentality that made Frame a success to begin with. They’re still looking for things they can disrupt or improve on.

“I think guys sometimes have an attitude of ‘let’s throw money at the problem’ where as I think women want to fix the problem,” says Black. “We work with other people to come up with solutions to the problem rather than just thinking, ‘we’ll buy a new one’.”

This constant need to adapt and grow is echoed in their personal lives. The two women had children within nine months of each other and as a consequence are now looking at their own working skills, how can they improve these?

“We’ve had to relearn how to work,” says Murphy. “We run a seven day a week business that’s open from 6am till 10pm and we have young children. One of the hardest things we’ve had to do is relearn our working habits ... Now we’re much more time aware, no more meetings for the sake of meetings. No meetings which take an hour when half an hour will do ... It’s been good for the company too, we’ve had to be a lot more structured with our time and they’ve appreciated that.”

They’re probably the fittest female entrepreneurs with young children that you’re ever going to meet but do they have any advice for others starting a similar journey?

“You have to have the right attitude and a lot of energy,” says Black. “Understand that you’ll probably lose your life for a short amount of time. Or a long amount. Get a strong team around you, whether that’s mentors or just your family.

“The reason why we’re here and why we’ve done as well as we have is because there is two of us and we complement and support each other all of the time ... If both of you are equally involved you drive each other on and if one of you is having a bad week then the other person can be the lead and vice versa. In short have a partner in crime.”