I've always been a firm believer in cross-training. I try to incorporate other forms of exercise besides running into my weekly workout regimen, whether it's swimming, spinning, weights, climbing, or yoga. Lately I've taken on power walking or speed walking. Why? Because it most closely resembles the action of running's forward motion while giving my body, especially my joints a rest.
It's really quite simple. I try to walk fast, about a 15 minute mile (4 miles/hour). I focus on form, keeping my posture tall and my head up. My arms swing naturally and bent at the elbow at a 90degree angle, almost as if in a running motion. I make sure not to overextend my stride and keep each step feeling natural. Racewalkers do a hip roll kind of motion with their strides, but I haven't quite got the hang of that. Unlike running where it's more efficient to land on the balls of the feet, with speed walking, land on the heel then roll the foot forward for a push off.
Since I'm not a rockstar runner like some people I know, I've used power walking as a way of taking a break during some past ultras I've done without losing significant amounts of time. It's also very helpful when climbing hills. I find it more efficient and less taxing to speed walk up the inclines instead of jogging up them.
So for 3 weeks now, twice a week, for about an hour, with a friend, I enjoy the trails, the streets, the beach, the hills, and the neighborhoods around here, slowing down just enough to smell, hear and appreciate my surroundings while still getting a great cardio workout and putting in valuable "on my feet" time.
Another benefit of walking–it's so much easier to carry on a conversation.