As a physical therapist, Pat Agostino was frustrated that his clients’ insurance would often run out just as they were starting to feel better.

He’d have to turn them loose without knowing whether they’d continue with their programs or give up and regress.

Agostino’s answer was to start a health club largely to cater to clients still in need of physical therapy but no longer covered by their insurance.

He and his brother, Jim Agostino, and wife, Karen Agostino, both also physical therapists, opened Peoplefit in Woburn, one of a number of clubs stepping up to fill a gap in the health care system.

"Every three months there is a formal evaluation with a physical therapist. We see whether people are making their goals or whether we need to modify their programs," Agostino said. "In addition, if someone injures themselves here or outside, they can see a physical therapist who will do an evaluation on them. If we can help them here, we help them. Otherwise, we send them to their physician."

Some health clubs have long been tied with physical therapists. But the numbers are growing, and clubs are adding more related health services such as acupuncture, massage therapy or even medical imaging tests.

"It’s part of a larger trend of the fitness clubs positioning themselves as part of the health care continuum," said Brooke Correia, spokeswoman for the International Health, Raquet and Sportsclub Association. "

Some health clubs have gone so far as to rent space to physical therapists and doctors. Others have aligned themselves with hospitals.

The Dedham Health and Athletic Complex has long worked with New England Baptist Hospital and Beth Israel Deaconess Medical Center on orthopedic services. More recently, it has worked with Joselin Diabetes Center to develop a special exercise program for people with diabetes.

The club’s high tech equipment is used to keep track of those members’ blood sugar levels, as well as their workouts to document the benefits. Club owner Lloyd Gainsboro hopes that one day insurance plans will cover such workouts as an alternative to drugs.

"We can provide exercise as a medicine," Gainsboro said. "It will take time for the medical community to figure out how to use it, but I don’t think we’re far away."

Such programs may play an even more important role as insurance providers push off costs on to consumers.

More insurance companies are offering so called consumer-driven health plans, which have high deductibles. In those cases, consumers may be looking for cheaper alternatives, or they may work harder to stay healthy.

From a health club’s perspective, offering extra services can help attract members in an increasingly competitive market.

Health Club membership has grown 35 percent in the last five years to 41.3 million. At the same time, the number of health clubs has grown by 75 percent.

"It’s very important in order to differentiate yourself," said Patty Daly, general manager of the Boston Athletic Club. "Anyone can offer treadmills and equipment."

The club has physical therapists, chiropractors and sports therapists on hand, among other services.

"With the diversity of the marketplace, you have to have a variety to help more people," Daly said. "Our members know they have someone on site if something hurts or if it doesn’t feel right."