Moist heat therapy has been believed to be more effective at warming tissues than dry heat, because water transfers heat more quickly than air. Clinical studies do not support the popular belief that moist heat is more effective than dry heat. Moist heat results in the perception that the tissue is heated more deeply. In fact, recent studies indicate that vasodilation, the expansion of the blood capillaries (vessels) to allow more blood flow, is improved with dry heat therapy. Expansion of the blood capillaries is the primary objective of heat therapy. Heat therapy increases the effect on muscles, joints, and soft tissue. Heat is typically applied by placing a warming device on the relevant body part.