Quotes of the Day

Guys, imagine if you could work out for 20 minutes just three times a week, lose weight and vent your frustrations at the same time. Then envision doing that at a gym without mirrors, free weights or treadmills. One more thing: you can sweat and burp without insulting women because it's a men-only club. Boys, welcome to Blitz.

In the 14 years since the first Curves fitness club for women opened, the single-sex, express-gym business has exploded, accounting for close to 25% of the entire U.S. health-club market. Figuring what works for women should do just as well for men, a number of male-only gyms — like Blitz — have recently sprung up around the country.

Blitz was launched last year by Scott Smith, 46, a former Curves franchise owner who wanted to adapt for men that company's quickie regimen. Today Smith counts 86 Blitz locations in the U.S. and Canada. (There's even a franchise in Guatemala.) The gyms, many of them found in strip malls, are set up like mock boxing rings, with members moving between machines and punching bags at the sound of a bell that rings every 30 seconds. "I don't care what your size or strength is," says Smith. "At the end of two 10-minute circuits, you'll wear yourself out and get blitzed."

As with Curves, the gender-restrictive Blitz policy hasn't yet been successfully challenged in court. In 2003 a suit against Curves's women-only policy in Wisconsin resulted in a new bill exempting single-sex fitness centers from the state's discrimination statutes. Curves executives believe men-only gyms won't work because males don't need the sense of support that women crave. But, says Brooke MacInnis of the International Health, Racquet & Sportsclub Association trade group: "The jury is still out."

Blitz also offers something that Curves doesn't — a chance to play Muhammad Ali, if only for 20 minutes. "At other gyms I'd sit on a stationary bike for 45 minutes and never see results," says David McWilliams, 42, a manager at Louis Vuitton. "But here it's really fast-paced. You really have to move around."

• Jeffrey Ressner