Comparison of Cervical Flexor Muscles Thickness During Cranial-Cervical Flexor Exercise According to Pressure Levels and Eye Directions in Healthy Subjects

Abstract

Purpose:The purpose of this study is to investigate differences of cervical flexor muscle thickness (i.e., sternocleidomastoid muscle and deep cervical flexor muscles) depending on levels of pressure bio-feedback unit and eye directions during cranial-cervical flexor exercise in healthy subjects. Methods: A total of 30 subjects (12 males and 18 females) who had no medical history related to musculoskeletal and neurological disorders were enrolled in this study. They were instructed to perform cranial-cervical flexion exercise with adjustment of five different pressures (i.e., 22 mmHg, 24 mmHg, 26 mmHg, 28 mmHg, and 30 mmHg) using a pressure biofeedback unit, according to three different eye directions (i.e., 0°, 20°, and 40°). Muscle thickness of sternocleidomastoid muscle and deep cervical flexor muscles was measured according to pressure levels and eye directions using ultrasonography. Results: In results of muscle thickness in sternocleidomastoid muscle and deep cervical flexor muscles, the thickness of those muscles was gradually increased compared to the baseline pressure level (22 mmHg), as levels in the pressure biofeedback unit during cranial-cervical flexion exercise were increasing. In addition, at the same pressure levels, muscle thickness was increased depending on ascending eye direction. Conclusion: Our findings showed that muscle thickness of sternocleidomastoid muscle and deep cervical flexor muscles was generally increased during cranial-cervical flexion exercise, according to increase of eye directions and pressure levels. Therefore, we suggested that lower eye direction could induce more effective muscle activity than the upper eye direction in the same environment during cranial-cervical flexion exercise. This is an Open Access article distribute under the terms of the Creative Commons Attribution Non-commercial License (Http:// creativecommons.org/license/by-nc/3.0.) which permits unrestricted non-commercial use, distribution,and reproduction in any medium, provided the original work is properly cited.

The Importance of Optimal Gaze Direction on Deep Neck Flexor Activation in Chronic Neck Pain

“…The CCFT is generally performed while looking slightly downward [ 19 ]. For individuals without CNP, DNF and SCM activation has been shown to change according to gaze direction in the CCFT [ 30 ]. In this study, changes in LC and SCM muscle thickness were measured using ultrasound images.…”

“…The DNF contracted ratio maintained a similar value as the degree of gaze direction increased, but, in contrast, the SCM contracted ratio increased as the degree of gaze direction increased. In a study that applied the CCFT to individuals without CNP, the SCM contracted ratio increased as the degree of gaze direction gradually increased to below 20° and below 40° [ 30 ]. In previous studies, SCM activation showed a specific pattern of increase with increasing gaze direction and direction of rotation angle (0°, 15°, 30°, and 45°) [ 31 ].…”

“…With the subject in the CCFT position, the air-filled pressure sensor unit was set to the pressure of measured maximum strength, and ultrasound imaging of the longus colli was performed in each of the four steps (0 • , 20 • , 40 • , and 60 • ) of the pre-installed guideline of gaze direction. The SCM was measured [30]. At that time, the movement of the neck joint was limited to allow only a change in gaze direction.…”

“…During CCFT performance, the gaze direction should be slightly downward [ 19 ]. A recent study on subjects without CNP reported that as the line of sight increased above the horizontal line (0°) to 20° and 40° during cranio-cervical flexion, both DNF and SCM activity increased positively [ 30 ]. This is different from previous studies showing that DNF and SCM activity are negatively related during CCFT performance, and instead, the activity of both muscles was shown to increase according to the gaze.…”

Effects of respiratory reeducation exercise using a pressure biofeedback unit on the quality of life of persons with stroke

“…The pressure biofeedback device consists of a meter and a flat pocket pneumatic pump, where the force generated by the contraction of the deep muscles is transferred to the pressure biofeedback device to measure the pressure. The unit is mmHg [16] (Figure 2).…”