CoStar reported that fitness centers, health clubs and gyms accounted for 8.8% of new leases signed so far this year by retail chains in the U.S., according to a story yesterday in The Wall Street Journal. At this point last year health clubs and gyms accounted for 7.9% of new leases by retail chains.

U.S. health clubs now occupy more than 70 million square feet, a 57% increase since 2007. The International Health, Racquet and Sportsclub Association says that health club membership increased 10.8% in 2010 to more than 50 million members. Membership had been relatively stagnant for several years.

The story quotes representatives from Gold’s Gym and L.A. Fitness, both of whom are planning to expand. Gold’s Gym, which currently has 500 U.S. locations, intends to add 17 sites this year and 30 next year. L.A. Fitness has 370 clubs and plans to open 250 more in the next five years.