Question

Picking up a heavy box from the floor is best performed with bent legs and a relatively straight back. simply bending at the waist (and keeping the legs straight) makes it more difficult for the low back muscles to generate a strong contraction, and they are likely to become damaged. which of the following best explains why the back muscles generate such a weak contraction

O They are overstretched, resulting in poor overlap between thick and thin filaments
O Muscle fibers in these muscles are too thick in diameter
O Stimulation to these motor unit is subthreshold
O The muscle fibers are fast-twitch and therefore fatigue quickly

Answer 1

The back muscles generate a weak contraction when lifting with straight legs and a bent waist because they become overstretched. The proper technique is to lift with bent legs and a straight back, using the leg muscles to minimize forces on the spine and avoid muscle strain or spine injuries.

Step-by-step explanation:

Picking up a heavy box with bent legs and a straight back is the correct way to avoid injury. If someone lifts by simply bending at the waist with straight legs, the back muscles are overstretched, leading to poor overlap between the thick and thin muscle filaments. This poor overlap results in a weak contraction, making it more likely for the muscles to become damaged.

When lifting with a straight back and bent legs, the spine is indirectly protected because large forces that can cause injury are significantly reduced. While our hips, knees, and ankles are designed to handle similar forces, our spines are much more susceptible to injury. Therefore, engaging the stronger leg muscles during the lift minimizes the force exerted on the back muscles, preventing overstretching and injury.

When performing activities that involve heavy lifting, ensure the proper technique is used to preserve back health and prevent muscle strain and potential damage to the discs and vertebrae due to abnormal forces on the back muscles and spine.