The effect of an active vibration stimulus according to different shoulder joint angles on functional reach and stability of the shoulder joint

Abstract

[Purpose] The purpose of this study was to analyze the effect of an active vibration stimulus exercise according to shoulder joint angles on functional reach and stability of the shoulder joint. [Subjects and Methods] Thirty healthy male students participated in this study. Upper limb length of each subject was measured to obtain normalized measurement values. The exercise groups were as follows: group I (n=10, shoulder joint angle of 90°), group II (n=10, shoulder joint angle of 130°), and group III (n=10, shoulder joint angle of 180°). After warm-up, an active vibration stimulus was applied to the subjects with a Flexi-Bar. The Functional Reach Test and Y-balance test were conducted for measurement of shoulder stability. [Results] Analysis of covariance was conducted with values before the intervention as covariates to analyze the differences among the groups in the two tests. There were significant differences among the groups. According to Bonferroni post hoc comparison, group I showed greater improvement than group III in the Functional Reach Test, and group II showed greater improvement than group I and group III in the Y-balance test. [Conclusion] The effect of the exercise with different shoulder joint angles revealed that the shoulder joint has a certain effective joint angle for its functionality and stability. In addition, application of an active vibration stimulus with a Flexi-Bar can be a very effective tool for improvement of functionality and stability of the shoulder joint.

The effect of the shoulder stability exercise using resistant vibration stimulus on forward head posture and muscle activity

“…Muscle activity was measured using sEMG after bodyblade exercise and there was a significant decrease in SCM and UP and there was a significant increase in SA in this study. This result occurred because vibration stimulus less than 50 Hz produced during bodyblade exercise induced tonic vibration reflex on muscle and tendon activating proprioception feedback10, 17 ) . Lister et al showed that bodyblade training increases sense of position, movement and shoulder joint stability and decreases pain and physical symptoms from shoulder joint instability4 ) .…”

“…Thigpen et al showed that, in comparison with ideal posture, FHP causes SA muscle activity decrease and trapezius overwork during upper extremity evaluation6 ) . SCM, superficial neck muscle, muscle activity should be minimized for FHP improvement10 ) . Muscle activity was measured using sEMG after bodyblade exercise and there was a significant decrease in SCM and UP and there was a significant increase in SA in this study.…”

“…Thigpen et al showed that posture change due to FHP changes scapular movement and muscle activity when raising hand over head6, 10 ) . For FHP evaluation method, Harman et al used CVA and CRA as test inspector and analyzed FHP changes.…”

“…They were measured twice to calculate mean value. Smaller CVA and greater CRA increase FHP level10, 15 ) .…”

“…In other words, scapula stability exercise (SSE) that controls scapular position and movement can place thoracic cage to neutral position and return abnormal neck alignment due to head forward flexion to right position through muscle interactions in neck and shoulder. Treatment methods using SSE are currently being studied for neck stability, alignment and pain reduction4, 9, 10 ) .…”