Meanwhile, sportswear giant Nike said last October that the rate of sales growth in its female clothing ranges was outpacing that of its products for men.
Analysts say that the rise in sales of women's sportswear has been helped by an increased emphasis on the style of the clothing - making them look and feel as good as possible - which in turn has led to an increase in the number of women wearing such items as fashionable leisurewear.
And with the market being so valuable, it is not surprising that a growing number of small companies - predominantly led by women - are launching their own ranges of upmarket female sportswear.
Katy Biddulph didn't need gym membership when she launched her women's sportswear brand Striders Edge in London back in 2011.
Initially running the business from a second floor one-bedroom flat, she would get her exercise by carrying all her deliveries up and down the stairs.
The 31-year-old says: "It looked like a fairly big business to the outside world when I was just starting out, but I was receiving all my goods from the manufacturer in Portugal from a truck outside my flat.
"I had hundreds of garments landing in the street, and I had to get all the boxes up the stairs by myself. I never slept that first year, but I just knew there was a gap in the market that I could fill.
"Now I've got an office that overlooks the London Eye."
Ms Biddulph set up the business after previously working for fellow British women's sportswear company Sweaty Betty, where she designed and managed a number of product ranges.
Her industry experience and knowledge persuaded a number of private investors to back her venture.
Striders Edge's clothes are now stocked by UK retailers Harrods, John Lewis and House of Fraser, and the brand launched in the US in February. It also sells globally via its website.
Now with nine members of staff, Ms Biddulph says she wants to hit £2m in sales within the next 12 months.
She adds: "You want your customer to feel great and part of something. As a female, you know the standard concerns."
But just how do you convince women to spend more than £60 on a t-shirt or a pair of leggings?
"It's not as hard as you would think," says Brittany Morris-Asquith, spokesperson and designer for Titika Active Couture, a Canadian brand based in Toronto. "Women are always looking for something different.
"They're asking more questions about fabrics, and if they understand the construction that goes into it, they're willing to pay for a better product."
Since Titika's founder Eileen Zhang, 32, opened her first shop in Toronto in 2009, Titika has expanded to seven stores across the province of Ontario.
And in March of this year it expended its online sales to the US, with plans to ship globally later this year.
Ms Morris-Asquith adds: "We provide clothing to women that make them feel good, we encourage them to try on things that they would never think about."
Titika also offers free in-store exercise classes to promote a healthy lifestyle - from yoga and kickboxing, to zumba dance workouts. And inspirational slogans affixed above fitting room mirrors urge against body shaming.
'Double bottom line'
Catherine Elliott, a professor at the Telfer School of Management at the University of Ottawa, says that businesses such as Striders Edge and Titika share an ethos which is typical for female-led companies.
"They tend to have a double bottom line - to create wealth, but also to make positive change for girls and women," says Prof Elliott, who is co-author of a recently published book on the subject called Feminine Capital.