title: Effects of forward head posture on forced vital capacity and respiratory muscles activity.
abstract: [Purpose] This study investigated the effects of forward head posture on forced vital capacity and deep breathing. [Subjects] Twenty-six subjects, divided into the two groups (normal and forward head posture groups), participated in this study. [Methods] Forced vital capacity and forced expiratory volume in 1 second were measured using respiratory function instrumentation that met the American Thoracic Society's recommendation for diagnostic spirometry. Accessory respiratory muscle activity during deep breathing was measured by electromyography. A Mann-Whitney test was used to compare the measure variables between the normal and forward head posture group. [Results] Forced vital capacity and forced expiratory volume in 1 second were significantly lower in the forward head posture group than in the normal group. Accessory respiratory muscle activity was also lower in the forward head posture group than in the normal group. In particular, the sternocleidomastoid and pectoralis major activity of the forward head posture group was significantly lower than that of normal group. Activities of the other muscles were generally decreased with forward head posture, but were not significantly different between the two groups. [Conclusion] These results indicate that forward head posture could reduce vital capacity, possibly because of weakness or disharmony of the accessory respiratory muscles.
authors.affiliation: Department of Physical Therapy, College of Science, Kyungsung University, Republic of Korea.
authors.forename: Jintae
authors.initials: J
authors.lastname: Han
authors.affiliation: Department of Physical Therapy, College of Science, Kyungsung University, Republic of Korea.
authors.forename: Soojin
authors.initials: S
authors.lastname: Park
authors.affiliation: Department of Physical Therapy, Graduate School of Clinical Pharmacy and Health, Kyungsung University, Republic of Korea.
authors.forename: Youngju
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Physical Therapy, College of Science, Kyungsung University, Republic of Korea.
authors.forename: Yeonsung
authors.initials: Y
authors.lastname: Choi
authors.affiliation: Department of Physical Therapy, College of Science, Kyungsung University, Republic of Korea.
authors.forename: Hyeonnam
authors.initials: H
authors.lastname: Lyu
keywords: Breathing muscle activity; Forced vital capacity; Forward head posture