Identification of exposed body segments and risk levels in specialized construction tasks involving upper limbs above shoulder level

BackgroundMusculoskeletal disorders are common among specialized construction workers due to repetitive, physically demanding work. However, biomechanical risks and the specific involvement of body segments in vaulted roof construction remain insufficiently characterized.ObjectiveIdentify the most exposed body segments and measure biomechanical risk in vaulted roof construction.MethodsThis observational study took place at six construction sites. Thirteen workers participated: six vault masters and seven helpers, all actively working on vaulted roof construction. Each worker completed six work cycles. We conducted task analysis, static biomechanical analysis, and the Susan Rodgers postural assessment. We measured muscle load as a percentage of maximum voluntary contraction (%MVC).ResultsTask analysis identified critical upper limb postures in both workers. The master vaulter spent 51% of the work cycle with their arms raised above shoulder level while handling significant loads, while the helper maintained similar postures for 90% of the cycle without significant loads. %MVC values exceeded recommended limits in the master vaulter left wrist (18%), left shoulder (24-25%), and right (26%). In the helper, both shoulders showed moderate muscle demand (%MVC: 14-16%). Susan Rodgers' method indicated a high-priority strain in the shoulder and arm during the master vaulter key postures, while the helper presented a low to moderate risk.ConclusionVaulted roof construction requires sustained overhead work and elevates strain on shoulders and wrists. The biomechanical risks are notably higher in the master vaulter than in the helper, underscoring the need for targeted ergonomic measures to reduce muscle strain and prevent occupational musculoskeletal disorders.