Changes in Activation of Serratus Anterior, Trapezius and Latissimus Dorsi With Slouched Posture

OBJECTIVE: To compare quantitative muscle activation between erect and slouched sitting postures in the muscles around the scapula, and to investigate the correlation between the angle of thoracic kyphosis and the alteration of muscle activity depending on two different sitting postures. METHODS: Ten healthy males participated in the study. Unilateral surface electromyography (SEMG) was performed for serratus anterior, middle trapezius (MT), and lower trapezius (LT), which are scapular stabilizer muscles, as well as latissimus dorsi. Participants elevated their shoulders for 3 seconds up to 90° abduction in the scapular plane, tilting 30° anterior in the coronal plane. They were told to hold the position for 10 seconds and voluntary isometric contractions were recorded by SEMG. These movement procedures were conducted for three times each for erect and slouched sitting postures and data were averaged. RESULTS: Activities of MT and LT increased significantly more in the slouched sitting posture than in the erect one. There was no significant correlation between kyphotic angle and the area under curve of each muscle. CONCLUSION: Because MT and LT are known as prime movers of scapular rotation, the findings of this study support the notion that slouched sitting posture affects scapular movement. Such scapular dyskinesis during arm elevation leads to scapular stabilizers becoming overactive, and is relevant to muscle fatigue. Thus, slouched sitting posture could be one of the risk factors involved in musculoskeletal pain around scapulae.

The Effects of Bolus Volume and Texture on Pharyngeal Pressure Events Using High-resolution Manometry and Its Comparison with Videofluoroscopic Swallowing Study

BACKGROUND/AIMS: The purpose of this study was to develop new parameters of high-resolution manometry (HRM) and to applicate these to quantify the effect of bolus volume and texture on pharyngeal swallowing. METHODS: Ten healthy subjects prospectively swallowed dry, thin fluid 2 mL, thin fluid 5 mL, thin fluid 10 mL, and drinking twice to compare effects of bolus volume. To compare effect of texture, subjects swallowed thin fluid 5 mL, yogurt 5 mL, and bread twice. A 32-sensor HRM catheter and BioVIEW ANALYSIS software were used for data collection and analysis. HRM data were synchronized with kinematic analysis of videofluoroscopic swallowing study (VFSS) using epiglottis tilting. RESULTS: Linear correlation analysis for volume showed significant correlation for area of velopharynx, duration of velopharynx, pre-upper esophageal sphincter (UES) maximal pressure, minimal UES pressure, UES activity time, and nadir UES duration. In the correlation with texture, all parameters were not significantly different. The contraction of the velopharynx was faster than laryngeal elevation. The durations of UES relaxation was shorter in the kinematic analysis than HRM. CONCLUSIONS: The bolus volume was shown to have significant effect on pharyngeal pressure and timing, but the texture did not show any effect on pharyngeal swallowing. The parameters of HRM were more sensitive than those of kinematic analysis. As the parameters of HRM are based on precise anatomic structure and the kinematic analysis reflects the actions of multiple anatomic structures, HRM and VFSS should be used according to their purposes.

High Resolution Manometry Analysis of a Patient With Dysphagia After Occiput-C3/4 Posterior Fusion Operation

Many reports of changes in cervical alignment after posterior occipitocervical (O-C) fusion causing dysphagia are available. The clinical course can range from mild discomfort to severe aspiration. However, the underlying pathogenesis is not well known. We report an 80-year-old female with videofluoroscopic swallowing study evidence of aspiration that developed after occiput-C3/4 posterior fusion. Pharyngeal pressure was analyzed using high resolution manometry (HRM). Impaired upper esophageal sphincter opening along with diminished peristalsis and pharyngeal pressure gradient were revealed by HRM to be the main characteristics in such patients. The patient fully recovered after a revision operation for cervical angle correction. Distinct pressure patterns behind reversible dysphagia caused by a change in cervical alignment were confirmed using HRM analysis.

Facilitating Effects of Fast and Slope Walking on Paraspinal Muscles

OBJECTIVE: To quantify the activation of the paraspinalis muscles (multifidus and erector spinae) at different walking velocities and slope with surface electromyography. METHODS: This study was a prospective experimental study involving ten healthy male participants. Surface electrodes were placed over the multifidus and erector spinae muscles at the L5 and L3 level. After the electrode was placed at the lumbar paraspinalis muscles, electromyography signals were recorded over 20 seconds. Data were collected three times during the walking exercise at a 0degrees gradient with the speed from 3 to 6 km/hr. At 7degrees gradient and 15degrees gradient, data were also collected three times but a walking speed of 4 km/hr. The area under the curve was calculated for quantitative measurement of muscle activation. RESULTS: While the muscle activation was increased at higher walking velocities at the L5 and L3 levels of the multifidus, the erector spinae muscle activation did not show any change at higher walking velocities. At L3 level of the multifidus and erector spine muscles, the muscle activation was significantly increased in 15degrees gradient compared to those seen in at 0degrees gradient. At L5 level, the multifidus and erector spinae muscle activation in 0degrees gradient was not significantly different from that those seen in 7degrees or 15degrees gradient. CONCLUSION: Fast walking exercise activates lumbar multifidus muscles more than the slow walking exercise. Also, the mid lumbar muscles are comparatively more activated than low lumbar muscles when the walking slope increases.