As is often the case in life, the simplest things are often the best. This applies to exercise too. For example, one of the best forms of exercise, running, is a direct outgrowth of one of the first things we learn to do—walk. Also running, often forbidden as small children (as in "I told you kids, no running!"), can reap great physical benefits as we get older.

Indeed, along with swimming, running offers one of the best overall workouts. But running does have its drawbacks. Prolonged running, especially on hard surfaces, can wreak havoc with your lower body. Unless you have an indoor track available to you, extremes of weather and temperature can complicate or curb even the most ambitious running program.

Never one to overlook a potential market, the exercise machine industry has responded with all types of indoor running machines. One that continues to grow in popularity is the home treadmill. Why? Here are three key reasons:

  • Convenience—Most people prefer not to exercise outside when it is cold, inclement, or dark. Even if you have access to an indoor track or a health club, finding a regular time to run during a busy week's schedule can be difficult. Owning a treadmill solves these problems. People who own one can exercise more often.
  • Physical benefits—Exercising on a treadmill has wide-ranging benefits. As Gregory Florez, president of Chicago's First Fitness Inc., points out, "Walking or running on a treadmill has great cardiovascular value for the heart, lungs, and circulatory system. It is a very efficient way to lose body fat, and since it is a weight-bearing activity, it has musculoskeletal benefits, as well." Because running can help to reduce stress, you may feel calmer and more relaxed after your workout.
  • Low-impact workouts—Despite all the benefits, years of walking or running can take its toll on feet, legs and hips, especially if you exercise on hard surfaces like asphalt or concrete. Treadmills, particularly higher-end models with built-in shock absorption properties, can reduce the stress placed on your feet, legs, and joints.

One of the biggest decisions for prospective buyers is whether to purchase a motorized or a non-motorized treadmill. What is the difference? Basically, with a motorized treadmill, you have to keep pace as the machine's motor moves the treadbelt (at a speed you electronically set). With a non-motorized treadmill, you push the belt with your feet, so you only go as fast as you push.

There are other differences as well. For one, non-motorized treadmills are much more affordable. Most are under $200.. Conversely, quality motorized models start at about $1,500 and can go as high as $5,000, depending on the features you are looking for. Non-motorized treadmills also take up much less space and, theoretically, can help you burn calories more efficiently, since you supply the muscle power to move the treadbelt.

Alas, however, this last fact is not necessarily true. Because you supply the muscle power, unless you are in good shape, you tend to move slower and tire more quickly. As a result you may actually burn fewer calories. Non-motorized models also have other drawbacks. Aerodynamics dictate that to get a non-motorized treadmill going, it has to be tilted on an incline. This can make running difficult if you are out of shape or not used to running. So, you derive less benefit. Finally, as you tire on a non-motorized treadmill, you will tend to push harder on one leg. This can make the motion of the treadmill choppy and harder to run on.