Every decade has its trends in physical fitness, and the ’00s will be remembered for the classes inspired by yoga and Pilates, the demand for which has grown so much that the publisher of Fit Yoga and Pilates Style is hosting a conference next month.

But the real change is in consumers’ rising standards for the places where working out happens. Gyms have turned into “fitness centers” with more amenities than most hotels and more marble than most banks. The multi-use palaces are not just for sweating and staying in shape; they’re for haircuts, massages, lunch, or a little shopping. But does a better locker room mean a better workout?

Part of the allure of high-end gyms is the variety and the space. The 140,000-square-foot Reebok Sports Club NY has enough offerings — swimming, basketball, weight machines, you name it — for members to switch their workout every day for weeks. Sectioned off from the sportiness are the Mind Body Studios, dotted with exotic flowers and smooth stones, where yoga, Pilates, and Gyrotonic instruction is offered.

But if you’re only going to use a gym for one or two of its facilities, why spend the money on a luxury gym? The amenities. A fancy fitness center gives clients more for their several hundred dollars in membership and monthly fees. Here, the showers sparkle. The lotion is smooth. The towels are big and fluffy. And the service doesn’t hurt. At the Sports Club/LA in Rockefeller Center, owned by the same parent company as Reebok, you can put in a breakfast order before your workout — and it will be ready for you when you’re done.

At Physique 57 — a compact, modern studio on 57th street where the classes are rooted in the Lotte Berk Method — the workout comes with some emotional inspiration, too. In the carpeted exercise room, a headset-wearing instructor barks out encouragement that competes with the strains of “What’s She Gonna Look Like With a Chimney on Her?” The locker room has a posting that congratulates the latest bride-to-be who has conquered the Bridal Countdown, which includes 15 classes in five weeks.

Still, it’s about more than good hair dryers and wedding arms. New York City’s multiplicity of gyms offers a sense of identity. Your choice of a gym can signal information about your finances, sexuality, and commitment to health. There are exclusive gyms and chain operations. There are pricey options and cheaper ones, plus scenes for players — and scenes for those who just want to play ball.

Working out at a place like Brooke Siler’s re:AB Pilates, for instance, means you want a toned body with a core of steel — no frills, please. At this small studio on Bleecker Street, the offerings are Pilates, really tough Pilates, and this-is-so-tough-I-can’t-walk-down-the-stairs Pilates. The classes and private sessions are given in a space with brick walls, hardwood floors, and area rugs. The gritty entrance looks like it could be the entrance to a warehouse.

In the end, however, if you work out at re:AB with a personal trainer frequently enough (a session with a principal instructor is $98 for one hour), you may spend as much as you would at the Reebok gym. You won’t enjoy the benefit of Reebok’s steam room, brand name, or social café, but who cares? You’ll have a body like Madonna’s.

This intensity of purpose also means that the people there are giving one another a little less of the hairy eyeball. It’s not just that men and women check each other out in the big gyms: It’s that women size up other women. At the Reebok Sports Club lobby, I caught corner-of-the-eyeball glances and the sharp daggers of implied competition — as I was filling out the insurance paperwork.

There’s a level of comparison to be expected anywhere that people are trying to improve their bodies. But at facilities devoted to a specific type of workout, there is a feeling of purpose and self-directedness that somehow reduces the dagger-eyes. At Sal Anthony’s Movement Salon on Third Avenue, which is located in the former theater known as Scheffel Hall, the people don’t seem to notice one another. They go about their Pilates, yoga, and various workouts and get on with it.

It all takes place without those nervous glares — and also without fluffy towels, smooth lotion, or egg-white omelets made to order.

pcatton@nysun.com