求翻译：of materials as well as awkward postures whereas loading and unloading vehicles. For preventive purposes, it would be important to distinguish the role of driving or the related WBV from other more established factors such as awkward working postures, or manual handling and also, to estimate their combined effects on back disorders. Furthermore, the outcomes in earlier studies have greatly varied and the defi nition of low back disorders has often been based on self-reports or radiologic fi ndings; rarely on a standardized clinical protocol and diagnostic criteria是什么意思？

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