Which of the following describes the role of the knees during a lift?

The role of the knees during a lift is critical for proper technique and safety. Bend and extend allow the lifter to maintain balance and effectively transfer force from the legs to the barbell. As the lifter descends into a squat or another lift, the knees flex, which helps lower the hips and body. This motion is essential for maintaining a proper center of gravity and balance.

In the upward phase, the knees extend, helping to drive the body up and generate power for the lift. This coordinated movement pattern ensures that the lifter engages the major muscle groups in the legs, including the quadriceps, hamstrings, and calves, which are all crucial for successful lifting.

The other options do not accurately describe the functional movement of the knees during lifts. Locking the knees at all times can lead to instability and potential injury, while suggesting that they should remain behind the toes does not account for the natural biomechanics of various lifts, where the knees may travel slightly forward. Lastly, the idea that knees should not move at all contradicts the necessary dynamic movement required for lifting safely and effectively.