What aspect of flexibility is most directly improved by regular assisted stretching?

Regular assisted stretching primarily enhances range of motion, which is the correct answer. This improvement occurs because assisted stretching involves a partner or practitioner helping to gently and effectively take a muscle or joint through its full range of motion. By employing techniques that target specific muscle groups, assisted stretching helps to elongate muscles and increase the elasticity of the tendons and surrounding connective tissues.

As muscles and tendons become increasingly flexible, the actual range through which a joint can move is expanded. This can lead to better overall physical performance as well as reduced risk of injury during activities that require extensive movement.

While aspects such as speed and agility, muscle endurance, and posture may also experience indirect benefits from enhanced flexibility, they are not the primary focus or most directly improved by regular assisted stretching routines. Strengthening the range of motion often lays the foundation for improvements in those other areas over time, but the immediate effect of such stretching practices is most keenly felt in the increased range of motion.