T'ai-Chi has developed a worldwide following of people, often with little or no interest in martial training, for its benefit to personal health. Medical studies of t‘ai-chi support its effectiveness as an alternative exercise and a form of martial arts therapy. It is believed that focusing the mind solely on the movements of the form helps to bring about a state of mental calm and clarity. Some other forms of martial arts require students to wear a uniform during practice. In general, tai-chi schools do not require a uniform, but both traditional and modern teachers often advocate loose, comfortable clothing and flat-soled shoes.