坡度與荷重對下肢負荷之影響

隨著企業規模的擴展，現代許多產業的作業流程普遍已自動化，然而，受到環境、設施規劃、資金等限制因素，人工物料搬運（Manual Materials Handling, MMH）的需求仍無法避免。其中，工作環境與搬運重量對於人員搬運具有相當程度的影響，而不良的搬運條件可能造成身體局部不適，甚至影響整體搬運姿勢、造成肌肉骨骼傷害（Musculoskeletal Disorders,MSDs）等風險。本研究欲探討物料搬運的過程中，斜坡環境、物料重量對於下肢關節角度及肌肉肌電訊號變化，期許能夠給予在物料搬運的改善與建議。受試者搬運不同重量的手孔箱，並行走於不同坡度的模擬地板，將手孔將搬運至工作臺。實驗包含兩項自變項，每個自變項分別有三種水準，分別是斜坡角度（0ﾟ、5ﾟ、10ﾟ）、搬運重量（空箱重、受試者體重10%、受試者體重20%），經由不同的實驗組合觀察受試者主觀費力程度（Borg CR-10）、肌肉負荷程度（%MVC，股直肌、股二頭肌、內腓腸肌、脛骨前肌）以及關節角度（髖關節、膝關節、踝關節）值，並使用敘述統計（Descriptive Statistics）及二因子多變量變異數分析（Two-way MANOVA）、皮爾森相關（Pearson correlation）進行統計分析。研究發現斜坡角度、搬運重量兩項因子對於主觀費力程度、肌肉負荷程度均有明顯的影響，關節角度變化僅在髖關節有顯著影響。不同搬運重量對於肌肉負荷程度有較明顯的影響，而關節角度變化僅在斜坡角度有明顯差異；主觀費力程度在搬運重量間，受試者對於搬運重量W2與空箱重具有較明顯的差異，搬運重量W1與空箱重間評量則無明顯變化，而在斜坡角度方面，坡度A3與A1間評分有明顯的差異，但A2與A1則無明顯的變化。綜合研究結果，建議坡度0度至5度時，建議搬運重量約體重10%~20%，坡度10度時，搬運重量約體重10%，對於肌肉骨骼傷害最小。

關鍵字

坡度,荷重,下肢

並列摘要

With the expansion of enterprise scale, automation is widely applied in many operation processes of modern industrial. However, even these modern industries can’t still avoid being affected by environment, facility planning and financing constraints, the demands of manual material handling (Manual Materials Handling, MMH) still exist. Among these constrains, operation environment and material weight of carrying are two major factors which often cause occupational hazards needed to be concerned. Poor handling conditions may cause localized uncomfortable and affect handling posture of worker. Finally it will result in Musculoskeletal Disorders(MSDs）. The purpose of this study is to investigate the influence of inclined surfaces and the weight of carrying load on the joint angles and muscle EMG changes of lower limbs in manual material handling, and hopes the results could offer suggestions and improvements in manual material handling. Participants used both hands to carry a hand-hole box with different weight of object inside and walked on different slope floors to transport the box to a work stage. Experiment contains two independent variables which are inclined surface and load conditions. Each independent variable has three levels respectively. The levels of inclined surfaces are 0ﾟ, 5ﾟand 10ﾟthree different slope angles, and the levels of load conditions are empty weight, 10% of participant weight and 20% of participant weight. The physiological indices such as percentage of maximal voluntary contraction (%MVC) of rectus femoris, biceps femoris, gastrocnemius and tibialis anterior as well as joint angle values of hip, knee and ankle joints were measured through different experiment combination. The subject Borg CR-10questionnaire was used to investigate subjective effort degree. Descriptive statistics, two-way MANOVA and Pearson's correlation were used to analyze the collected data. The result showed that the effects of inclined surface and load condition on Borg CR-10 and %MVC are significant, but on joint angle only in hip is significant. The effects of different load conditions on %MVC were more significant, and inclined surface only affected joint angle. In the Borg CR-10 questionnaire, participants considered that carrying the load W2 (20% of participant’s weight) and empty weight had obvious significant differences, carrying the load W1 (10% of participant’s weight) and empty weight had no significant differences, however. In terms of slope angle, the effects of slopes of A1 (0o) and A3 (10o) were obvious difference, however, the effects of A2 (5o) and A1 (0o) had no significant difference. Based on our findings, to reduce the musculoskeletal injuries, it is recommended when slope angles are between 0 to 5 degrees, the recommendation of load weight is 10%~20% of body weight, and when slope angle is up to 10 degrees, the recommendation of load weight is about 10% of body weight.