Yoga isn't an aerobic exercise. It does little to develop the cardiovascular system or metabolic capacity, but it's excellent for building flexibility and muscle tone. Thai researchers found that it can build chest and breathing muscles, which can improve lung capacity. Twenty-nine healthy subjects practiced yoga for six weeks, emphasizing postures such as the cat, tree and camel to develp chest wall muscles. Yoga increased chest expansion (size of chest during maximum inspiration), vital capacity (capacity to blow air from the lungs rapidly) and forced expiratory volume in one second. Yoga boosted lung function by increasing the strength of breathing muscles or reducing airway obstruction, which could benefit people with lung disease. Increasing lung capacity isnt the same as increasing cardiovascular or endurance fitness. At sea level, lung function doesn't limit oxygen transport capacity in healthy people.

FASEB, April 2006