The effect of hand tools’ handle shape on upper extremity comfort and postural discomfort among hand-woven shoemaking workers

Hand tools are widely used in a large number of occupations. Many workers have to use hand tools to accomplish their duties. This may cause work-related Upper Extremities Musculoskeletal Disorders (UEMSDs). The present study was conducted in Iranian hand-woven shoe industry to (a) investigate the design of hand tools currently used in hand-woven shoemaking operation and (b) design/redesign the tools' handles based on anthropometric tables and ergonomic principles. Based on Iranian workers' anthropometric tables, new handles with different shapes were designed and made for hand tools currently used in hand-woven shoemaking operation (e.g., awl and cloth cutting tool). Hand postures and postural comfort and discomfort were investigated via rating technique using Comfort Questionnaire for Hand Tools (CQH) and upper extremities body map. The results of CQH showed that the handle shape had a significant influence on the hand posture and perceived postural discomfort in the upper extremities. The new ergonomically designed handles were perceived to be more comfortable compared to the traditional ones. Additionally, the new handles improved the hand posture during the operation and reduced the severity of discomfort in the upper extremities compared to the tools with conventional handles. The findings of this study revealed that designing the hand tools’ handles based on ergonomic principles and using anthropometric tables could improve the hand posture, increase comfort, and decrease discomfort in the upper extremities. By this means, reduction in work-related UEMSDs is expected.