High impact exercises such as running and jumping can be hard on the bones and joints and cause fractures and injuries. Because swimming does not put stress on those areas, it is a great way to get in shape with less chance of injury. Swimming is often recommended by doctors and therapists as a way to strengthen muscles when recovering from an injury. The buoyancy of the water provides a cushion for movement. Our bodies have about the same density as water, which prevents stress to the joints since the water becomes a support.