Abstract
PURPOSE: “Chest gripping”is an abnormal trunk muscle activation pattern limiting lateral expansion of the lower thorax, which may reduce thoracic extension or even cause low back pain (LBP). Hypertonic upper abdominal muscles may be a cause. The serratus posterior inferior (SPI) is considered an only antagonist to the chest gripping. TheaimofthisstudywastodetermineaneffectiveexercisetoactivatetheSPI. SUBJECTS: A healthy male volunteer was recruited. METHODS: Activities of the 3 trunk muscles during 8 maximal exertion tasks and normalized surface-electromyography values were obtained. The wire electrodeandthesurface electrode were used for the measurement. RESULTS: The SPI were effectively recruited during active trunk rotation at end sitting and side lying, ipsilateral shoulder hyper-flexion compensated with trunk rotation from the all-fourʼs position. CONCLUSION: The SPI has an effect to which it carries out the rotation of the trunk by one-side activity. Therefore, it is surmised that SPI has the effect that pulls an ipsilaterally lower ribs back.
