In Pilates, which of the following practices was a significant innovation brought by Joseph Pilates?

Joseph Pilates' introduction of springs for resistance was a significant innovation in the development of Pilates as a method of exercise. This unique feature allowed for controlled resistance during workouts, which enabled practitioners to develop strength, flexibility, and stability in a way that was both safe and effective. By utilizing springs, Pilates created apparatus such as the Reformer, which provided adjustable levels of resistance, facilitating a diverse range of exercises suitable for various fitness levels and rehabilitation needs.

Springs allow for smooth and controlled motion, which is foundational in Pilates. This innovation not only made the exercises more versatile but also highlighted the importance of control and precision in movements, which are key principles of Pilates practice. This stands in contrast to the other options, which, while beneficial in their own right, do not represent the core innovations that define the Pilates method as envisioned by Joseph Pilates himself.