Which of the following is NOT an example of a cool-down activity?

High-intensity interval training (HIIT) is characterized by short bursts of intense exercise followed by rest or lower-intensity periods. It is designed to significantly raise the heart rate significantly, which is the opposite of what cool-down activities are intended to do. During a cool-down, the goal is to gradually decrease the intensity of the workout, allowing the heart rate and breathing to return to their normal levels.

Cool-down activities are usually lower in intensity and focus on transitioning the body from the heightened state of exercise to a resting state. Activities such as stretching exercises, slower walking or jogging, and cycling at a low pace effectively help in this transition, promoting recovery and reducing the risk of muscle stiffness or soreness. Therefore, incorporating high-intensity intervals would not fall under the appropriate definition of a cool-down activity.