Abstract
This study examined the effect of chest mobilization on intercostal (IC) muscle stiffness using the IC muscle shear modulus. Sixteen healthy young men participated on two days with a minimum of 24 h between the stretching and control conditions (SC and CC). The tasks were resting breathing and deep breathing. The IC muscle shear modulus and muscle activity and rib cage circumference were measured before and after each condition. In the SC, IC stretching was performed for 1 min x 5 sets. In the CC, resting breathing, in a sitting position, was performed for 5 min. In the SC, the IC muscle shear modulus decreased significantly (p < 0.05) at maximum inspiration in the deep breathing task, but there was no significant difference in the CC pre- and post-intervention. The results suggest that IC muscle stretching decreases IC muscle stiffness and improves muscle flexibility and that the IC muscle shear modulus may measure the effectiveness of chest mobilization.