Water aerobics is often associated with senior fitness programs, prenatal exercise and injury rehabilitation. It's typically not thought of as a challenging workout. But that depends on how you do it. The same types of interval training you can do on land can also be done in the pool, and with less stress on your joints and muscles.
The buoyant forces of water provide a cushioning effect, which protects your muscles, joints and bones from impact. This does not necessarily make it less challenging. Water is 800 times denser than air and facilitates high energy expenditure with minimal risk of injury, explains University of New Mexico exercise physiologist Len Kravitz in an article on the University's website.
Kravitz reviewed the research studies associated with various forms of water exercise and reported that aerobic activities that used the arms and legs in chest-deep water required a significant increase in energy expenditure, equal to or greater than the same exercises performed on land.
Interval training is a mode of cardiovascular exercise in which you alternate periods of high-intensity exercise with periods of recovery at a lower intensity. During the high-intensity periods the goal is to work as hard as you can. Since you can't sustain exercise at that intensity, the recovery periods allow your heart rate to normalize before performing the next high-intensity interval.
In terms of increasing cardiovascular endurance, interval training may meet or exceed the effectiveness of longer steady-state workouts. Interval training may also aid fat loss in two ways. First, you burn more calories during the high-intensity period than with steady-state exercise. By repeating these intervals, your total calorie burn may be higher than a steady-state workout of similar duration.
Secondly, interval training may increase your body's ability to burn fat. In a study published in the Journal of Applied Physiology in 2007, researchers had female subjects sprint on an exercise bike for 30 seconds, then pedal slowly for four minutes, repeated 10 times. After seven sessions performed over a two-week period, participants showed significant improvement in capacity for fatty acid oxidation during exercise.
Aquatics Interval Exercises
Any water aerobic interval training program should begin with at least five minutes of moderate aerobic exercise in the pool to warm up. This might include jogging in place and doing some dynamic stretches such as leg lifts while reaching the opposite hand to the opposite foot.
During high-intensity intervals, which may last from 30 seconds to two minutes, the exercises become more intense. Big motions with the legs and arms create intensity as they work against the resistance of the water. The goal is to move explosively and as fast as you can.
Some examples of high-intensity aquatic exercises include:
Plyometric jumping jacks: Explode up as high as you can spreading the arms and legs, then land bringing the arms across the chest and the legs together.
Simulated tire runs: Run through the water as fast as you can, bringing your legs out and in as if you were running through tires. Pump your arms up and down or back and forth at the same time.
Mogul jumps: Jump side-to-side, tucking the knees into the chest and landing with feet together. Push your palms out in the opposite direction of your feet to create more resistance.
During the recovery intervals, stay active. You must keep your entire body moving to gain aerobic benefits and maintain your body heat in between high-intensity segments. Recovery activities may include marching in place, side-stepping, jogging in place and forward and backward walking.