Aquatic exercises are usually used for rehabilitation and for alleviating symptoms of arthritis and other muscle aches. But water can also be a very effective fitness tool. It provides resistance, so you can build muscle, while supporting your body weight at the same time and easing certain exercises on the joints and bones. This significantly decreases the chances for getting injured, especially if the person is obese or in poor physical shape. Water is 784 times denser than air, which means that every kick and slide is a full-body workout. Your core, hips, glutes and arms feel it the most.