The warnings are on equipment and fitness professionals often preach it to clients, especially older ones: “Consult your doctor before beginning an exercise program.”

“But who does it?” asked Jeri Engen, director of the Alegent Health Lakeside Wellness Center. “We all know the answer to that one: Not many.”

The fact is middle-aged people who skip the doctor's visit risk overexerting underused muscles, including the heart.

Alegent Health's medically-based fitness center offers personalized service to determine fitness levels of prospective members as well as members during their membership.

“Our friendlier, no spandex atmosphere makes us much more attractive to those who don't feel comfortable in competitive, hard-body gyms,” says Engen. “They think, ‘I should be doing something, but I need someone to hold my hand and nudge me on.”

The average age of members at Lakeside Wellness Center is over 50, and 45 percent of members are over 55. In contrast, people over 55 represent only about 14 percent of the membership at non-medical gyms, according to the company.

“Each member gets individualized feedback,” says David Sharp, D.O. “Members get direction about what to do based on their health status, health risks and conditions, as well as their personal interests.”

Keeping fit keeps people out of the physician's office, Dr. Sharp says. Fit people are less likely to develop lifestyle-related illnesses, such as heart disease and hardening of the arteries that arise from sedentary lifestyles.

“Best of all,” Sharp added, “are the results of using fitness as preventive medicine. It does work. It's as powerful a prescription for health care as all the latest medical technology that we've got.”