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Thoracic breathing Thoracic breathing is a method of producing expansion and contraction of the ribcage. In thoracic breathing this is achieved by the sets of muscles attached to the ribs and other structural parts of the body, as well as muscles acting between the ribs themselves. To inhale, certain groups of these muscles act to pull the ribcage upward, forward and outward, expanding the thoracic cavity and drawing air into the lungs. Exhalation occurs by the passive recoil of the ribcage as these muscles relax. Another set of muscles compresses the ribcage even further than this starting position, if complete expulsion of air from the lungs is required.
Thoracic breathing is a less efficient type of breathing than abdominal breathing, but is required during increased physical activity, when a greater volume of air must be drawn into the lungs. In comparison with abdominal breathing, more muscular effort is required to perform thoracic breathing for the same quantity of air. Thoracic breathing is often associated with situations of mental stress and tension, as its function is to assist the lungs to gain more oxygen in a stressful situation. However, the tendency to continue this kind of breathing often remains long after the stressful situation has disappeared, creating bad breathing habits. In fact, research has found that over 20 percent of the normal population tends towards habitual thoracic breathing.
Thoracic breathing is inefficient, because it brings the bulk of air into the middle lobes of the lungs, which are poorly supplied with blood. The alveoli towards the outer lung surface tend to expand more than is optimum, while the central alveoli do not open out properly, which creates uneven gas diffusion. If the outer alveoli open wider than is preferable, as occurs in certain disease states such as asthma and emphysema, they can also lose their elasticity. Then they remain in a fixed, open position with very little excursion for taking in air. The chest appears large and barrel shaped, but the lungs do not move well during respiration. Therefore, thoracic breathers need to take occasional deep breaths that will fill their lungs from top to bottom.
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