背景與目的：非特異性頸部疼痛為電腦使用者最常見也最困擾的症狀。電腦作業時，長時間靜止且不佳的坐姿可能是造成頸部疼痛主要問題之一，因此在過程中維持一個較理想且正確的姿勢，對於預防及減輕症狀是非常重要的。再者，相關研究指出在長時間電腦作業下，頸部疼痛患者維持姿勢的能力會下降。而臨床上，各式物理治療已被用來幫助矯正姿勢及其相關疼痛症狀; 但其長時間電腦作業的維持效益並不顯著。甚至連健康人都需要額外口頭及觸覺回饋才能維持長時間好的坐姿。過去文獻曾證實姿勢性回饋可以有效改善久坐時造成的下背痛及姿勢，但是否能夠幫助頸部疼痛患者改善姿勢、與減少肌肉負荷及不適感仍未知。因此，此研究主要目的為探討使用即時姿勢性回饋對於頸部疼痛患者及健康人在長時間電腦作業下，脊椎姿勢和肌肉活化程度的效用。方法：本研究一共招募42人，分別為21位非特異性頸部疼痛患者及21位健康受試者。所有受試者皆須進行各1個小時，兩個狀況 （有無使用姿勢回饋裝置）的打字測試。打字測試過程中測量脊椎姿勢、肌肉活動程度、主觀不適感、以及震動式姿勢性回饋的總次數。研究使用三維動作分析系統測量脊椎姿勢，包含頭部前傾、頸部屈曲、上頸椎、下頸椎、上胸椎及下胸椎的角度。雙側頸部、胸部豎脊肌、與上斜方肌平均肌肉活化程度則以表面肌電圖作量測，並與習慣坐姿之平均值做標準化。資料統計則使用混合型重複量測變異數分析，比較脊椎姿勢、肌肉活化程度、以及主觀不適感在兩組間 (頸部疼痛患者及健康人)、兩個情形 (有無使用姿勢回饋裝置)、以及長時間下 (姿勢與肌肉活化:一小時中每隔10分鐘; 不適感:一小時中每15分鐘)的變化或差異。震動姿勢性回饋的總次數則是以曼-惠特尼U檢定來檢視兩組間效益。結果：當使用姿勢回饋時，明顯有較小的頸部屈曲、上頸椎、下頸椎與下胸椎角度以及雙側頸椎豎脊肌與左側上斜方肌活動程度。而頸部疼痛患者比上健康受試者則是有明顯較高的上胸椎角度及右側上斜方肌活化程度。主觀不適感則是隨著時間逐漸上升。頸部疼痛患者在頸部和肩膀兩區域皆明顯提升，而健康受試者只發生在肩膀。在比較兩組間的震動回饋總次數方面則是沒有任何顯著差異。 結論：本研究所使用之姿勢回饋可以有效幫助輕微不適之頸部疼痛患者以及健康受試者在進行長時間打字時，調整至一個較挺直、頭部較不前彎且兩邊頸椎豎脊肌和左側上斜方肌活動程度較低的姿勢。未來研究需進一步探討姿勢回饋對疼痛程度較高患者的效益以及其長期使用之效果。

Introduction and purpose: Non-specific neck pain is one of the most annoying symptoms among computer users. The prolonged, static, and restrained poor posture may be one of the main problems to cause neck pain during computer works. Thus, to maintain an ideal spinal posture is essential for preventing and reducing symptoms in prolonged computer works. Several interventions of physical therapy were performed in clinical practice to help regain a proper posture. However, the evidences were still limited during prolonged status. Moreover, the studies revealed that the neck pain patients have inability of maintaining posture. Even the asymptomatic people needed some tactile or oral feedback to maintain posture during prolonged sitting. Postural biofeedback had been proved that it can improve prolonged sitting posture and pain among healthy and low back pain patients. However, whether using postural biofeedback is helpful to improve sitting posture, related muscle activity and reduce neck discomfort in neck pain adults associated with prolonged typing is still unknown. The purpose of this study was to determine the effects of real-time postural biofeedback on spinal posture and muscle activity while performing prolonged typing in neck pain and healthy adults. Methods: A total of 42 participants were recruited in this study and 21 who has non-specific neck pain (neck pain group) and 21 are asymptomatic (healthy group). Spinal posture, muscle activity, subjective discomfort and the frequency of biofeedback were recorded while performing a 1-hr typing task under two conditions, with and without postural biofeedback for all participants. Spinal posture was measured using the VICON motion analysis system with 6 cameras and presented in 6 angles including head tilt, neck flexion, upper cervical, lower cervical, upper thoracic and lower thoracic. Muscle activity of bilateral upper trapezius, cervical erector spinae and thoracic erector spinae was measured using the Delsys surface EMG and presented as mean EMG that also was normalized with the EMG of habitual sitting. Mixed model repeated measure ANOVAs were used to assess the differences in spinal posture, muscle activity, subjective discomfort between two groups (neck pain and healthy group), two conditions (with or without postural biofeedback) and over time (every 10 minute in spinal posture and muscle activities; every 15 minute in subjective discomfort). Post hoc analysis was performed as indicated. The Mann-Whitney U test was used to estimate the differences in the frequency of biofeedback between groups. Results: The significantly smaller angles of neck flexion, upper cervical, lower cervical, lower thoracic and reduced bilateral cervical erector spinae and left upper trapezius muscle activity were found in the condition of using postural biofeedback devices. Greater upper thoracic angle and right upper trapezius muscle amplitude were presented in neck pain adults. The subjective discomfort level was increased over time in neck among neck pain adults, in shoulder among both groups. No differences were shown in the frequency of vibration between two groups. Conclusions: Postural biofeedback could help adjust to a more upright and less forward flexion posture, and prevent the bilateral cervical erector spinae and left upper trapezius muscle overloading during prolonged computer works in both neck pain patients and healthy adults. This study supports the use of postural biofeedback for improving posture and reduced muscle activities during prolonged computer works. Further studies should consider assess the effects of using postural biofeedback in neck pain patients with higher severity or investigate its long-term effects on postural correction and pain relief.

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