Photo by Skip Lawrence Planet Fitness is open at the Vista Shops on the Golden Mile. Josh Carlisle, left, is general manager and Jerry Woods, is operator and part owner. Purchase this photo

The 19,000-square-foot fitness center has more than 80 pieces of cardio equipment, including treadmills, ellipticals and arc trainers. It also has two circuits of Cybex strength machines, an express workout area, six tanning booths and massage chairs.

Victor Brick, owner of the Frederick location, owns 10 centers.

He and John Craig, a corporate spokesman, said the key to Planet Fitness' success is that it has no salespeople, no juice bars or child care that can increase costs.

Memberships are $10 a month for access to one club, $19.99 a month for access to all Planet Fitness centers. The higher fee also includes free tanning, unlimited guest privileges and half-price cooler drinks.

Core customers at Planet Fitness are first-time or occasional gym users. The club's philosophy, known as Judgement Free, has a low tolerance for bodybuilders, Craig said.

Each center has a "Lunk Alarm," a flashing police car light and loud siren that the front desk personnel trigger if someone slams free weights onto the floor or is grunting too loudly when working out.

"It's a mainstay of our clubs, and our way of discouraging lunkish behavior that's a turn off to most people, yet par for the course at a lot of gyms," Craig said.

Brick said the Frederick club eventually will be open 24 hours at day.

Launched in 1992 in New Hampshire, the company has 254 clubs in 29 states and more than 1 million members.

Inc. magazine recently listed Planet Fitness as the top fitness center in its 5,000 fastest-growing private businesses review. From 2004 to 2007, Planet Fitness revenues rose from $8.4 million to $48.5 million.