water

Because of buoyancy, impact on joints is reduced by about 50% when you’re submerged to the waist and 75% less when you’re submerged to the chest.

It’s a new, if not odd, sight inside some public pools in Washington, D.C.: people kicking submerged punching bags, spinning on poles that rise from the water, jumping up and down on floating boards.

For about six months, hundreds of residents have been getting their feet wet with new “HydroSuite” classes, part of Mayor Muriel Bowser’s #FitDC initiative. HydroPole, HydroKick and HydroBoard join HydroSpin (the water version of land favorite, spinning), offered since 2015.

While hydro fitness has been around for decades, its cool factor has shot up in the past few years. Now you can find hydro classes cropping up in gyms in New York City’s Hell’s Kitchen and college campuses such as the University of Oklahoma. They are extremely popular internationally, as well, in countries such as Canada, the United Kingdom and the Netherlands.

The re-brand partly comes thanks to the promotional efforts of the nonprofit Aquatic Exercise Association. The AEA’s director of education, Julie See, says that “getting more people to understand the benefits of water . . . and the wide range of classes now available has helped to promote water exercise as beneficial for all ages and abilities.” Aqua classes are no longer primarily viewed as the classes your grandmother takes.

And that’s because so many of the hip new hydro classes are serious calorie burners, at 500 to 800 calories an hour. With a focus on cardiorespiratory fitness, muscle strength and endurance, flexibility, neuromotor training, and body composition, See says hydro classes can be easily modified to meet different exercise needs. The biggest con is the chlorine or bromine used to keep pools clean, which can be a skin irritant for some participants.

I’ve never strayed far from lap-lane workouts, so this trend had escaped me until a chilly Sunday morning in March, when my attention was diverted from my usual back and forth to a group of people chest-deep in water kicking and punching at boxing bags as the teacher called out instructions.

The classes were established by Rashid Jones, a Department of Parks and Recreation specialist certified in aquatic fitness. Having “seen the end result” of too little exercise while working as an autopsy technician at the D.C. Medical Examiner’s office and George Washington University Hospital, Jones is on a personal mission to help D.C. residents: “The doctors I worked with taught me that your body . . . your health and wellness is what you make of it.”

It looked different and challenging, so I decided to try some classes. First, I joined in for part of a HydroKick class, alternating kicking and punching a bag with Wynonia Harris, 44. Harris, who had been taking the class since October, knew what she was up against: water resistance.

According to the AEA, water is 800 times denser — more viscous — than air. And the resistance is bidirectional. So, when kickboxing in water, my quads were working in one direction and my hamstrings in the other. This provides a more balanced workout, See says.

“It was something different and it was in the water, so I figured it would be less pressure on my knees,” Harris says about her decision to try HydroKick. She’s right. Because of buoyancy, impact is reduced by about 50 percent when you’re submerged to the waist and 75 when you’re submerged to the chest.

Along with buoyancy and viscosity, research shows that hydrostatic pressure and thermodynamics play a role in enhancing a water exerciser’s fitness. Hydrostatic pressure — a “multidirectional pressure” that pushes on the chest in water — makes breathing more difficult. Kinetics research suggests this added value forces even fit people who take to the water to develop stronger assistive breathing muscles.

“I never thought that I could sweat so much in the water,” Harris says. We do, indeed, sweat during water exercise, but because of thermodynamics, the water transfers heat away from the body faster than air.