What type of exercise is the most appropriate in cool down as they help the muscles to relax

Stretching as part of your cool-down

Stretching helps to relax your muscles and restore them to their resting length, and improve flexibility (the range of movement about your joints). As a guide, allow 10 minutes of post-exercise stretching for every one hour of exercise.

Static Stretching

This is a very effective way to increase flexibility. Static stretches should be used as part of your cool-down routine to help prevent injury. Using static stretching as a maintenance stretching program will also help reduce your risk of injury