A brisk walk is a form of exercise that involves walking at a faster pace than normal. It is often used as a way to increase the intensity of a workout and can be beneficial for cardiovascular health. The term 'brisk walk' can also be used to describe a type of TROT, which is a four-letter gait of a horse where the legs move in diagonal pairs. This type of TROT is usually faster than a regular TROT and requires more energy from the horse.