Aerobic Benefits of Swimming Our affinity to water goes far deeper than the pools or oceans we swim in. It is found on a cellular level of our being. “According to H.H. Mitchell, Journal of Biological Chemistry 158, the brain and heart are composed of 73% water, and the lungs are about 83% water. The skin contains 64% water, muscles and kidneys are 79%, and even the bones are watery: 31%.” Competitive swimmers put their hearts into every practice, literally. Aerobic “with oxy