In this low-impact, slow-motion exercise, you go without pausing through a series of motions named for animal actions — for example, "white crane spreads its wings" — or martial arts moves, such as "box both ears." As you move, you breathe deeply and naturally, focusing your attention — as in some kinds of meditation — on your bodily sensations. Tai chi differs from other types of exercise in several respects. The movements are usually circular and never forced, the muscles are relaxed rather than tensed, the joints are not fully extended or bent, and connective tissues are not stretched. Over time, tai chi improves balance, develops muscular strength in the legs, and helps relieve any unnecessary tension from the body. Tai chi can be easily adapted for anyone, from the most fit to people confined to wheelchairs or recovering from surgery.