Peter Vi, Hon. B.Sc. (Ergonomics), Project Coordinator, CSAO Construction Safety Association of Ontario An
effective way to reduce upper limb MSIs Because of the repetitive, often heavy manual material handling required to lift, carry, lower, and install reinforcing steel, rodworkers suffer a high number of musculoskeletal injuries (MSIs). MSIs are injuries of the muscles, nerves, tendons, ligaments, joints, cartilage, and spinal discs. Typically they are non-traumatic, that is, caused not by sudden accidents such as trips or slips but by overexertion and repetition over time. Purpose
Rebar-tying tasks were evaluated using an electro-goniometer (to measure wrist angles) and force sensor tape (to measure hand and grip forces). Seven rodworker apprentices and one instructor took part in the research.
Results Results indicate that rebar-tying machines can have a positive benefit in preventing MSIs to the upper limbs. The machines also allow workers to work upright and thus avoid the bending, twisting, and awkward static trunk posture of manual tying at ground level. In addition, working with rebar-tying guns requires only one hand. Workers can lean on their knee with the other hand and thereby support their trunk. This in turn decreases some of the muscle activity and muscle fatigue that occur with manual tying. Summary
One way to decrease these risks is to use automatic rebar-tying machines. CSAO research indicates that these machines can help to decrease hand-grip force and repetitive wrist motions such as bending, twisting, flexion, and extension. Future
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