24 Hour Fitness Founder Mark Mastrov Returns as Owner and Executive Chair Following Acquisition

January 7, 2026

24 Hour Fitness has announced that founder Mark Mastrov has returned to the company as owner and executive chair following an acquisition completed in partnership with LongRange Capital. The transaction positions Mastrov and LongRange Capital as new owners of the brand, supporting the existing executive leadership team led by President and CEO Karl Sanft.

Mastrov founded 24 Hour Fitness and grew the company from a single location into a national operator with hundreds of clubs and millions of members before selling the business in 2005. He later led the acquisition and expansion of Crunch Fitness, growing it to more than 550 owned and franchised locations prior to its sale in 2025. His return brings decades of industry experience back to the brand during what the company describes as a strong period of growth. ClubSolutions