BOSTON - Denver and Colorado have the highest rates of health club membership among the nation's cities and states, according to the 2005 IHRSA/American Sports Data Health Club Trend Report. The annual report has been conducted for the last 19 years by American Sports Data (ASD) and sponsored by the International Health, Racquet & Sportsclub Association (IHRSA).

A projected 21.8 percent of Colorado state residents (over the age of six) belong to a health club or fitness center, the study found. Utah residents follow closely with 20.8 percent of them belonging to health clubs or fitness centers, while 20.6 percent of Massachusetts residents belong.

Denver ranks as the top city in the country for health club memberships with 25.1 percent of its residents belonging to either a health club or fitness center. Columbus, OH, follows closely with 24.9 percent of its residents saying they are members, and 23 percent of the residents of San Diego belong to a health club or fitness center.

The study also showed that one-third of all health club members in the United States live in the South where obesity rates tend to be among the highest in the country. Interestingly, the South has experienced the greatest level of growth in health club membership of any region in the nation, increasing 29 percent from 10.7 million members in 1999 to 13.8 million members in 2005. The West has the next greatest number of health club members with 10.2 million followed by the North-Central region with 9.2 million members and the Northeast with 8.1 million members.