Final answer:
When lifting, your center of gravity should be positioned above your base of support with your back erect, using legs to lift the object for stability and back protection.
Step-by-step explanation:
When lifting something, your center of gravity should be positioned directly above your base of support, which typically means keeping it above your feet and between your legs. By doing so, you ensure that your body remains in a stable equilibrium and maintain proper balance. For optimal safety and efficiency, you should keep your back erect while using your legs to lift, which minimally stresses the relatively weaker spine.
For instance, while lifting a heavy object, employing a posture where your back is straight and legs bent to lower your center of gravity closer to the ground enhances your stability. Expanding the base of support, such as positioning your feet farther apart, can also increase stability during the lift. This is similar to a person balancing a load on their head where the center of mass needs to be directly above the neck vertebrae to reduce strain and maintain balance.
Figure illustrations suggest that the center of gravity for an adult is located above the hip joints and that the body is like a pencil balanced upright. Maintaining this alignment, especially when lifting, prevents excessive force on the back and maintains balance and stability.