During PNF stretching, what happens after the muscle is contracted isometrically?

After the muscle is contracted isometrically during PNF (Proprioceptive Neuromuscular Facilitation) stretching, the correct process involves allowing the muscle to relax before stretching it to a new endpoint. This relaxation phase is crucial as it takes advantage of the autogenic inhibition reflex, where a sustained contraction of the muscle leads to a subsequent reduction in its tension. By allowing the muscle to relax, it can achieve a greater level of flexibility and range of motion when moved into a stretch afterward. This technique is designed to enhance muscle lengthening and improve flexibility more effectively than static stretching alone.

In contrast, immediately putting the muscle through a range of motion without this relaxation does not optimize the benefits of PNF stretching. Subjecting the muscle to more resistance after contraction could lead to potential injury rather than improved flexibility. Maintaining the muscle in a static contracted state would negate the benefits of the stretching process, as the goal is to facilitate movement and promote relaxation rather than holding the muscle tightly.