Question

Back injuries are very common in humans and are often caused by lifting objects with the legs straight while leaning over; also known as "lifting with the back." Use the concepts learned in this lab to explain why one should "lift with the legs" rather than with the back. Make sure to discuss the forces and torques involved, and how they differ in the two lifting techniques.

Answer 1

Back injuries are some of the most common injuries that occur when handling heavy objects, for example, when working in truck loading and unloading jobs, or lifting weights in a gym.

This type of injury is mainly caused by incorrect posture or body position when handling these weights. In essence, it is recommended that the back remain rigid and upright to avoid pressure on the lumbar zone and the cervical discs, transferring the center of force towards the legs (which have a capacity to exert much greater force than the mid-torso and back area). low).

In this way, the torque or upward pushing force that lifts the manipulated weights arises from the hamstrings and quadriceps, rather than directly out of the waist area. This prevents injuries such as herniated disc or low back pain, which are very painful and difficult to treat.