If you'd like to exercise at home but want to select equipment that won't suffer that fate, the following guidelines might help.
If you're interested in running or walking, treadmills work well. In fact, in some cases, treadmills work better than running or walking outdoors. You can control your pace on a treadmill, which can protect you from opening your stride too much (important if you suffer from hamstring injuries), yet you still get the hip extension and knee flexion of a good running workout. A treadmill is also convenient; it's no fun to be five miles out on a run, feel a twinge and have to limp home. And they're low impact, so treadmills provide a good running bed if you plan to run for an extended period of time - say, if you're training for a marathon. If impact is a big issue for you, anti-shock treadmills are available from several companies, including Precor, Nautilus and Technogym.
An elliptical (a cross between a stationary bicycle and a treadmill) is a good choice if you need to minimize joint forces. If you're interested in cycling, consider a wind trainer, which lifts the rear wheel of your bicycle, making it stationary. For general fitness, wind trainers are ideal: You optimize your exercise time while also eliminating outdoor hazards such as cars, dogs, potholes, rain, snow, sun exposure, heat and humidity (not to mention the hassles of dealing with flat tires and finding a bathroom). They're also perfect for interval training because you can gauge each interval exactly - no wind or changing terrain to vary each interval. People have prepared for the cycling portion of triathlons using them exclusively. One downside: You miss out on honing your bike-handling skills.
For even more sophisticated indoor cycling, add a CompuTrainer - a computer-aided training device that offers you variable resistance as well as feedback on your speed, power, cadence, heart rate and RPMs. A CompuTrainer can even give you a "hill workout" by providing low RPMs in a big gear. You can also get software to run on your computer while you ride your CompuTrainer, which will allow you to race your friends or race the computer on a course simulating world championships, the Tour de France or the Race Across America.
If you're in the market for a universal-type gym device (one on which you can perform a number of different exercises), pay special attention to the machine's resistance throughout the range of each exercise. Those that use pulley systems with springs or elastic bands can have heavy resistance at the start of the lift but light resistance at the end. Spring-loaded systems can be light at the start but get heavier toward the finish. You want to find one with consistent resistance throughout the lift.
To ensure your home gym equipment stays dust-free, don't park it in front of a blank wall. Set it up near a TV, or get a book holder so you can sweat it out while reading your favorite book or newspaper.
( Eric Heiden, M.D., a five-time Olympic gold medalist speed skater, is now an orthopedic surgeon in Utah. He co-authored Faster, Better, Stronger: Your Exercise Bible, for a Leaner, Healthier Body in Just 12 Weeks (HarperCollins) with exercise performance physician Max Testa, M.D., and DeAnne Musolf. www.heidenothopaedics.com)