Walking can be done fast or slow, up or down hills, on a track or on a hike, or while carrying hand weights or a back pack.
People racewalk and waterwalk.
Walking is a popular form of exercise that can be done indoors or outdoors. It is quite easy on the knees, ankles, and back. Although not injury-proof, walking has a very low injury rate. Common walking injuries are problems related to pain in the ankles, feet, shins, Achilles, and knees. Take aspirin or ibuprofen to reduce inflammation.