Tread lightly. Make your own little switchbacks in the trail when going downhill. Walking straight down a slope’s fall line puts the greatest pressure on your feet, knees, and leg muscles and soft tissue in joints. To lessen that impact, especially on steep trails, I like to zigzag slightly in the trail—as if creating my own tiny switchbacks within the footpath – so that I’m landing with each foot at a diagonal angle to the fall line rather than stepping straight down it. Work on it, I think you’ll notice the difference once you get the knack of it.
Source: The Big Outside