Fig. (3) Method for measuring the extension angle of the thoracic vertebrae E: the center between the seventh cervical vertebra and the first thoracic vertebra; F: the midpoint between the sixth thoracic vertebra and seventh thoracic vertebra; G: the center between the 12th thoracic vertebra and 1st lumbar vertebra; Thoracic vertebra extension angle: based on the value of angle EFG (<EFG) at the position with the upper limbs hanging downwards, the change in <EFG at the position with the upper limbs elevated by 160°.