What aspect of the hamstring curl on the Wunda Chair reduces the risk of hyper-extension?

The correct answer focuses on the position of the back during the hamstring curl on the Wunda Chair. Maintaining a neutral spine and engaging the core while performing the exercise is essential to prevent hyper-extension of the lower back. If the back is not properly aligned, there is a significant risk of strain and injury as the movement of curling the legs may inadvertently cause the pelvis to tilt or the lower back to arch excessively, leading to hyper-extension.

In Pilates, proper alignment is critical for both safety and effectiveness; thus, ensuring that the back remains in a stable and controlled position helps to protect the spine throughout the movement. This alignment allows for targeted muscle engagement and reduces the chances of compensatory movements that might otherwise put undue stress on the lumbar region.

While the other choices, such as the use of both legs simultaneously, spring resistance level, and the speed of the movement, can influence the overall effectiveness and safety of the exercise, it is primarily the position of the back that plays a pivotal role in preventing hyper-extension during the hamstring curl.