A recent investigation by researchers from the National Institute for Occupational Safety and Health (NIOSH) describes how some of these WMSDs may occur. The investigation found that tying rebar at ground level using pliers increases the risk of developing hand-wrist and low-back injuries. The same report concluded that using a power tier may prevent these injuries.
A Washington, D.C. area union contractor requested NIOSH to conduct a study on a one-mile bridge that had over 2 million rebar ties. NIOSH investigators wanted to know if power tiers reduced WMSD risks for deck tying. The tying methods included pliers, battery powered tiers, and battery powered tiers with a 3 ft. extension handle. The extension handle allowed rodbusters to stand when tying the rebar.
Researchers measured the amount of wrist movement and forward bending rodbusters used with each tying method. Results showed that using pliers involved the most risk of injury. Using pliers required continuous wrist movements and unsupported stooping. Repeated or prolonged stooping may lead to lower-back pain and increase the risk of a more serious injury.
Using the power tiers caused less stress to the wrist and low-back. With the power tier, rodbusters used less wrist movements and supported their body weight when bending with free hand. As expected, using the extension handle...