Natural and forced arm reach ranges in sitting position

Arm reach ranges are important for manual workspace layout, products, and equipment design. To explore arm reach ranges in a sitting position, this study measured the reach ranges of left and right hands among 300 adults (150 males and 150 females) under two postures (natural and forced straight arms) at four operating heights. The results showed that arm reach range increased as operating height increased at levels below the shoulder. The forced reach (arms straightened forcefully) extended farther than the natural reach, showing a mean difference of approximately 23 mm. At suitable operating heights (700–800 mm), males exhibited farther arm reach than females, with a mean difference of approximately 60 mm. No significant differences in the reach range were found between right and left hands or among different age groups. These results support more precise layout of manual workspaces and more personalized design of workplace equipment.