Modular pools are used in aquatic rehabilitation because they provide a controlled and safe environment for patients to exercise in. The water provides buoyancy and support for patients with mobility issues or injuries, which allows them to move and exercise with less stress on their joints. Additionally, the resistance of the water can be used to provide a challenging workout for patients, which can help to improve strength and endurance. Modular pools are also used because they can be easily set up and taken down, making them a flexible option for rehabilitation centers that may not have a permanent pool on site.