Weight bearing exercise is defined as any exercise where the bones work against gravity to support the body, or where they work against other kinds of resistance, as in weight-lifting. This seems fairly straightforward, except that there are some activities where a lower amount of resistance creates a question of whether they are weight bearing or not. On popular fitness chat boards, some of the usual suspects are swimming, where the participant works against water instead of the cold hard ground, and cycling, where variable practices include different kinds of resistance.

According to most reports by fitness experts, elliptical machines are a great source of weight bearing exercise. As you are pushing down on the pedals, you are using lower body bones and muscles to propel the pedals forward. Add some of the variable resistance challenges that are featured on most elliptical machines, and you have a double dose of weight bearing activity, where the elliptical trainer becomes like a "weight training machine for the legs."

This kind of activity helps to build bone strength, according to scientists, and is useful in preventing conditions like osteoporosis later in life.

Elliptical machines frequently include calorie counting features. This gives you goal options, including timed goals and calorie burning goals. There's a great feeling in seeing your calorie burn count reach your intended goal, and this kind of informed workout is getting a lot of attention from many fitness beginners. Another dashboard feature is a heart rate monitor, where you can keep your heart rate in a specific target zone for optimal cardio work.

With many elliptical machines, you can also choose from variable resistance programs where the machine LED marquee shows increases and decreases in resistance that simulate walking up and down hills and mountains. Some machines even have variable inclines for working different muscle groups.

Although many activities actually provide weight bearing exercise, the real value of ellipticals, for many users, is in what they bring to the fitness training experience. For anyone who wants to simulate running, skiing or similar activities without a high impact that risks joint and bone injuries, elliptical machines are a great way to get physical challenges into a routine safely and efficiently. These machines are also popular for rehabilitation or therapy, and for anyone who has limitations that make treadmill or outside running unfeasible. Look for these machines in gyms and health clubs everywhere.