**2. Biomechanics of chest movement and thoracic spine**

Movement of the thorax is like the pump-handle pattern (Hammon, 1978). Movement of the chest wall is a complex function within the rib cage, sternum, thoracic verterbra, and muscles. Basic observation reveals chest configuration for abnormality of the spine or chest shape, for example, scoliosis, kyphoscoliosis, barrel, or pectus excavatum (Bates, 1987). Normally, in all joint movement at the end of expiration, the intercostal muscles are at a suitable length before contraction during inspiration.

In assessment, chest stiffness may be caused by muscle structure being applied directly in the supine, side lying or sitting position. Stretching the rib cage, rotating the trunk or lateral flexion of the trunk can be evaluated. Furthermore, suitable lengthening of soft tissue around the chest wall and respiratory muscles is related to the efficency of contraction force and chest movement. In the case of emphysematus lung or air trapping in COPD, abnormal chest configurature and reduced chest movement with shortened muscle length and weakness are experienced (Malasanos et al., 1990).

Finally, increasing chest movement with stronger contraction of respiratory muscles can help in gaining lung volume, breathing control and coughing efficiency, and reducing symptoms by improving aerobic capacity, endurance, functional ability, and quality of life.
