San Ramon, Ca — Mark Mastrov's abrupt resignation as chairman of the board of 24 Hour Fitness, San Ramon, CA, left some in the industry puzzled.

Mastrov, who founded 24 Hour in 1983, resigned effective Jan. 31. A brief notice of his resignation was sent about three weeks before that to 24 Hour employees.

“The way that it was communicated by the company to Mark's own colleagues was disrespectful,” says John McCarthy, former executive director of the International Health, Racquet and Sportsclub Association (IHRSA). “The debt that 24 Hour owes to Mark is immeasurable. The company could have and should have communicated Mark's resignation in a manner that unambiguously honored Mark. That didn't happen, which disappointed many people.”

A statement from 24 Hour said that Mastrov planned to pursue other opportunities. Mastrov could not be reached for comment.

In 1983, Mastrov borrowed $15,000 from his grandmother and bought a 10 percent stake in 24 Hour — which was then a 5,000-square-foot club in San Leandro, CA — before eventually buying out his partner. Today, 24 Hour is the highest-revenue producing company in the industry, serving more than 3 million members in more than 400 clubs worldwide.

Mastrov moved from CEO to chairman in 2006 after Forstmann Little & Co. named former Home Depot Executive Carl Liebert as its new CEO. The move came a year and a half after Forstmann Little & Co. purchased 24 Hour for $1.6 billion.

“Mark is still a young man,” McCarthy says. “To date, he has created, from scratch, a company that is the envy of the worldwide health club industry. No one has ever done before what he managed to do. It is a Horatio Alger success story of epic magnitude.”

Ray Wilson, who sold his 68-club Family Fitness Centers to 24 Hour in 1995 for $95 million, calls Mastrov “the greatest person that's ever been in the fitness industry. Period. Nobody, in my opinion, has come close to Mark.”

Mastrov's departure could give him more time to devote to Augie's Quest, an organization that raises money to find a cure for ALS, the disease that has afflicted Life Fitness founder Augie Nieto. Mastrov was the brainchild behind The Bash for Augie's Quest, a fundraiser that debuted at the IHRSA show in 2006. He was chairman for the first two events and remains on the founder's committee for the event. McCarthy is chairman of this year's event, which takes place March 7 in San Diego.

“Mark has played an instrumental role in the success of The Bash for Augie's Quest and also for Augie's Quest in general,” says Shannon Shryne, who coordinates Augie's Quest initiatives as the national director of business development for the Muscular Dystrophy Association, which has an ALS division. “Our hope is that he continues to stay involved. We're very confident that his future will be as successful as his past has been.”

In an e-mail forwarded through Shryne to Club Industry's Fitness Business Pro, Nieto wrote of Mastrov, “Mark and I have been friends for over 25 years. Your friendship is truly defined when adversity happens. Mark was one of the first people to reach out. He has held my hand and helped me have the courage to dream of a day that ALS will be a treatable disease, not a death sentence.”