What describes good body mechanics when lifting?

Bending the knees when lifting is a critical aspect of good body mechanics. This technique allows the lifter to use the strong muscles of the legs, which are better designed to handle heavy loads, rather than straining the back. When a person bends their knees, it helps lower the center of gravity, providing better balance and stability during the lift. This practice reduces the risk of injury, particularly to the lumbar region of the spine, which is prone to stress and strain when lifting improperly.

In contrast, bending at the waist can put excessive strain on the lower back, as it requires the spine to bear the load in a compromised position. Keeping the legs straight and bending at the hips can also lead to similar back strain because it doesn't engage the larger and stronger muscle groups effectively. Lifting with the back instead of the legs is one of the most common causes of back injuries, as it forces the spine to do all the work without the support and strength of the leg muscles. Thus, choosing to bend the knees is the safest and most effective approach when lifting objects.