This article is from the Alternative Medicine Therapies guide.
What sets Hatha yoga apart from some other forms of yoga and general exercise programs is that it places an equal emphasis on mental and physical fitness. This mind-body integration, proponents believe, is what helps Hatha yoga practitioners feel calmer and more "centered," and is why it's often recommended for stress reduction.
Hatha yoga concentrates on three areas: pranayama (breathing), asanas (postures), and dhyana (meditation). The controlled breathing of pranayama helps to focus the mind and is important for relaxation and meditation. Its deep, slow breathing patterns have a beneficial effect on the respiratory system: Studies show that people who do yoga regularly have lowered breathing rates and increased lung capacity. The postures, which include standing, balancing, forward and backward bends, and twists, strengthen the body, increase flexibility, and encourage relaxation. In addition, Hatha yoga has been shown to improve posture and increase circulation. Dhyana, the meditative aspect of yoga, calms and focuses the mind. All three practices build on and complement one another.
Although scientists don't know exactly how yoga produces its physiological benefits, some speculate that it does so primarily by reducing stress. It may also promote the release of endorphins, the body's natural painkillers.