Physiological Effects of Exercise in the Water

Water-based exercise is an effective way to achieve the same results as land-based exercise without the risks of joint damage and injury. In addition to the low-impact nature of water exercise, there are long-term physiological effects that significantly differ from land exercise. These include oxygen consumption, heart rate and muscle strength.

  1. Oxygen Consumption

    • Researchers Len Kravitz and J.J. Mayo explain in their 1997 paper that the total amount of oxygen consumed during exercise shows a significant decrease after approximately eight weeks of shallow-water exercise. This indicates an increase in cardiovascular health similar to what is seen after chronic land-based exercise. The results for deep-water exercise are not as clear, but it is not unreasonable to expect similar results.

    Heart Rate

    • One of the common measures of success for an exercise program is resting heart rate. When cardiovascular fitness improves, resting heart rate decreases. While a lower resting heart rate is seen with water exercise, it is not as reliable as land-based exercise. Heart rate during exercise varies with water temperature and depth, with cooler and deeper water decreasing sub-maximal heart rate during exercise. Consequently, exercise in shallow water at temperatures above 86 degrees Fahrenheit is more efficient at improving cardiovascular fitness.

    Muscle Strength

    • Kravitz and Mayo cite several studies that show significant increases in muscle strength after eight weeks of water exercise. Despite incorporating no specific strength exercises into the program, subjects performed better at specific strength and endurance exercises. Those with low levels of fitness prior to starting a water-exercise regimen generally show dramatic increases in strength while those with high levels of fitness are able to maintain strength through water exercise alone.

    Other Changes

    • Other changes that are not statistically significant include flexibility and body composition. While flexibility tended to increase from water exercise regimens, the results did not differ significantly from land-based exercise in either direction. Body composition, on the other hand, tended to show increases in total body fat after water exercise as opposed to land-based exercise. This is similar to the redistribution of, and increase in, total body fat that swimmers experience after prolonged training.