OCRA: a concise index for the assessment of exposure to repetitive movements of the upper limbs

TLDR

Work‑related musculoskeletal disorders of the upper limbs are widely reported, and existing literature and prior studies have highlighted occupational risk factors that can be quantified using NIOSH‑recommended procedures. The study proposes a concise index for assessing exposure to repetitive upper‑limb movements. The OCRA index is calculated by comparing the daily number of upper‑limb actions performed to a recommended baseline of 30 actions per minute, adjusted for force, posture, and other risk factors. Preliminary results indicate that the index can integrate multiple risk factors and classify occupational scenarios with high exposure. Keywords include WMSDs, Concise Exposure Index, and Assessment of Exposure.

Abstract

Abstract In the light of data and speculation contained in the literature, and based on procedures illustrated in a previous research project in which the author described and evaluated occupational risk factors associated with work-related musculoskeletal disorders of the upper limbs (WMSDs), this paper proposes a method for calculating a concise index of exposure to repetitive movements of the upper limbs. The proposal, which still has to be substantiated and validated by further studies and applications, is conceptually based on the procedure recommended by the NIOSH for calculating the Lifting Index in manual load handling activities. The concise exposure index (OCRA index) in this case is based on the relationship between the daily number of actions actually performed by the upper limbs in repetitive tasks, and the corresponding number of recommended actions. The latter are calculated on the basis of a constant (30 actions per minute), which represents the action frequency factor; it is valid—hypothetically—under socalled optimal conditions; the constant is diminished case by case (using appropriate factors) as a function of the presence and characteristics of the other risk factors (force, posture, additional elements, recovery periods). Although still experimental, the exposure index can be used to obtain an integrated and concise assessment of the various risk factors analysed and to classify occupational scenarios featuring significant and diversified exposure to such risk factors. Keywords: Wmsds Concise Exposure Index Assessment Of Exposure