Tread carefully. Step onto stable, relatively flat rocks and earth when walking downhill. That not only reduces your risk of slipping and falling, but those feet-friendly platforms act as small, natural braking mechanisms for your body, thus relieving your muscles of some of that effort. It may sound minor, but over the course of many miles and thousands of steps, it can make a difference. I frequently walk along the tops of the bigger rocks that are sometimes set in place at the edges of trails to keep hikers from wandering off the trail; they usually provide a stable platform (they won’t roll) and make a descent easier on my legs.
Source: The Big Outside