Do not look down your nose on the eliptical machine! So many of my friends who are runners would not be caught dead on one. Instead they go out and do five miles of road work rain or shine three or four times a week. They end up with twisted ankles and plantar fascitis and all kinds of other problems, and then they hit the road again before they are properly healed.

I go on the eliptical machine three to four times a week and save the "real" running for the basketball court or an actual 5K or 10K race. I never get injured running anymore, and I think my cardio health is even better than it was when I ran -- and got hurt -- all the time.

Even if you prefer real running, why not give your legs a break once or twice a week and use either the eliptical machine or a stationary bike to keep your heart and lungs pumping but give your joints and bones a rest.