An Atlanta-based private equity firm that invests in franchisers has acquired a "significant" but minority interest in fast-growing Anytime Fitness of Hastings.

Anytime CEO Chuck Runyon said the company chose Roark Capital Group as an equity partner because it is the "pre-eminent private equity firm in franchising." Terms weren't disclosed.

"We've been contacted by dozens of private equity firms over the years who have wanted to invest in the company," Runyon said. "Roark … understands our philosophy and values the importance of supporting profitable and happy franchisees. Roark will help us improve system-wide performance, grow internationally and assist us in building our health and wellness platform."

Anytime Fitness, which Runyon co-founded in 2002, has opened at least 250 clubs in each of the past six years and expects systemwide revenue of $736 million this year.

Runyon and Dave Mortensen, Anytime's co-founder and president, will continue as the two top executives.

Roark Capital Managing Directors Erik Morris and Steve Romaniello have joined the Anytime Fitness board of directors and will provide strategic counsel and operational support.

"As a result of an innovative and differentiated consumer proposition and a commitment to thoughtful growth through franchising, Anytime Fitness has become a leader in its industry," Romaniello said in a statement. "We look forward to supporting the continued success of the Anytime Fitness brand."

Roark Capital previously has invested in 30 franchised businesses that boast $16 billion in systemwide revenue and operations in 50 states and 71 countries. Among them: Arby's, Carl's Jr., Cinnabon and Massage Envy. The firm has $3 billion in equity under management.

Runyon and Mortensen recently acquired Denver-based Waxing the City, and they are now franchising that line of specialty waxing studios.

Another Twin Cities-based fitness franchiser, Snap Fitness Inc. of Chanhassen, announced in January that TZP Capital Partners II fund of New York had purchased the stake of its previous strategic investor after a sale process that attracted more than 100 potential buyers. Snap has about 2,000 clubs nationwide, most of which are owned by franchisees.

Anytime Fitness, which expects corporate revenue of about $85 million this year from franchise fees and other sources, said it has considered raising capital through a public stock offering, but added that that is unlikely in the "foreseeable future." The company declined to discuss its profitability or value.

Anytime Fitness says it is the world's fastest-growing gym franchise, with more than 2,400 clubs open around the clock every day, with 2 million members on five continents. The clubs tend to be smaller than large competitors that have swimming pools and basketball courts, but offer a variety of exercise equipment.

Neal St. Anthony • 612-673-7144