When is it necessary to reduce lifting weights by 10%?

Reducing lifting weights by 10% when twisting beyond 45 degrees is necessary due to the increased risk of injury associated with lifting and twisting simultaneously. The human spine and core muscles have limitations in how much they can safely support during such movements. Twisting while lifting puts additional strain on the back, which can lead to serious injuries, including muscle strains or disc injuries. Therefore, when a lift involves a twist beyond 45 degrees, adjusting the weight limit helps ensure safety and minimizes the risk of injury by recognizing the increased physical demand on the body.

In contrast, the other options relate to lifting scenarios that may not inherently increase the risk to the same extent as twisting. For example, the guidelines for lifting directly or from the floor typically incorporate proper techniques that can be safely executed without the additional risk that twisting introduces. Reducing the weight based solely on the height of the lift or lifting technique without taking into account the twisting motion would not address the heightened risk of compromise to spinal safety.