Here are suggestions from fitness experts at the University of Minnesota, University of St. Thomas and St. Catherine University for people considering high-intensity fitness programs.

Consult your doctor: Do this before you start any new exercise program, regardless of intensity. Even with some health limitations, clients may be able to tackle aggressive fitness programs by starting more slowly.

Check out the trainers: Interview the teacher or coach for your class to determine that person's expertise -- preferably certified by a national organization such as the American College of Sports Medicine or National Strength and Conditioning Association. If buying a DVD, go to that company's website to check the trainer's credentials or call the company to ask.

Picking a program: At fitness centers, talk with trainers about your goals -- weight loss, more energy, overall fitness, for instance -- and ask which programs might be best for you and how to build up to high-intensity programs. Many fitness centers offer free or reduced-cost intro sessions to let you test-drive a program. Some require courses or boot camp programs to teach basics and techniques before admitting a client to a high-intensity program. Many DVD producers such as Beachbody offer a 30-day return policy.

Plan to stick with it: Pick a program that you'll continue. For fitness, continued exercise is far more important than which program you choose. If the program or trainer you choose is not right, switch to a different one but don't stop exercising.