Final answer:
The first rule of lifting is to keep your back in a straight position to avoid excessive force on the spine, reducing the risk of muscle strain and spinal injuries.
Step-by-step explanation:
The first rule of lifting is to keep your back in a straight position. This is because when you lift with your back rounded, the force on your spine is significantly greater than if you were to lift with a straight back. The spine is relatively weak compared to other parts of the body, such as the hips, knees, and ankles, which can handle larger forces. When lifting properly, using the legs to raise the load and keeping the back straight, the forces on the back are approximately 5.6 times smaller, thus minimizing the risk of muscle strain and damage to the discs and vertebrae. It is crucial to avoid actions such as twisting slowly, bending at the waist, or using your arms to do most of the lifting, as these can lead to increased chances of injury.