Effect of Assistive Device for Neck Retraction (ANR) on Neck Muscles during Neck Retraction Exercise

摘要

Recent epidemiological studies indicate that office workers often experience neck and shoulder pain1' 2 Although workers with these types of work-related musculoskeletal disorders (WRMSDs) recover with time through rest, the rate of reoccurrence is as high as 60%2> 3) The causes of neck pain include abnormal neck and head posture as well as excessive neck movevment4). At the atlanto-occipital joint, an anterior transition of the head, which is defined as a forward head posture (FHP), develops a long moment arm for the cervical extensor (CE) muscles to counteract the load of the head5). This long moment arm generates a low muscular requirement for CE, with greater activation of the upper trapezius, so that weakness in the CE often occurs in patients with a FHP6- 7) Conversely, the sternocleido-mastoid (SCM) muscle is shortened in FHP5). An effective therapeutic exercise for FHP may include neck retraction, for activating the CE and reducing the SCM. Such an exercise should include extension of the lower and flexion of the upper cervical areas, the opposite of FHP5). However, few materials are available for assisting or guiding this type of exercise with respect to direction and resistance. Therefore, the purpose of the present study was to develop an exercise device for assisting neck retraction exercises and to investigate the device's effectiveness.