What instruction should the charge nurse give to a UAP who is bending at the waist to lift a 20-pound box?

Bending at the knees when lifting heavy objects is recommended as it utilizes the strength of the legs to lift rather than putting strain on the back. This technique helps to maintain proper body mechanics, reducing the risk of injury, especially to the lower back. By keeping the back straight and bending at the knees, the individual can maintain better stability and leverage while performing the lift, which is essential for handling any significant weight, such as a 20-pound box. This approach promotes safety and is a fundamental principle in lifting techniques taught in health and safety training programs.