What principle is NOT a part of stretching?

The principle that is not part of stretching is immediate high-impact routines. Stretching is fundamentally about preparing the muscles and joints for activity by promoting flexibility and preventing injury. It typically involves low to moderate intensity exercises that allow for gradual adaptation of the muscles and tendons.

Incorporating immediate high-impact routines goes against the purpose of stretching, which aims to increase range of motion and flexibility rather than subjecting the body to sudden, intense forces. Such high-impact activities can increase the risk of injuries, especially if the body hasn't been adequately warmed up or stretched.

Other principles involved in stretching include warm-up procedures, which help increase blood flow to the muscles, and gradual intensity, which emphasizes the need to allow muscles to adapt to stretching in a controlled and progressive manner. Hold duration is also key, as maintaining a stretch for a specific time allows for elongation of the muscle fibers and connective tissues, enhancing flexibility.