During spinning class, I often find myself wishing I was in a pool. For one, water would make the sweat dripping down my back less noticeable. Two, it has to be easier to sneak a break when the instructor can’t see your legs below the surface.A new study presented this week at the Canadian Cardiovascular Congress suggests there might also be other - more important - benefits to hydro-spinning.The study analyzed cardiovascular data from 33 young, healthy participants who performed the same workout on a dry land stationary bike and on a water stationary bike.Also called hydro-riders or aqua bikes, water stationary bicycles are anchored to the bottom of a pool so that cyclists are submerged up to their shoulders. Resistance can be added by changing the pedal size or, in some bikes, the angle of plates in the wheels.Researchers found that participants’ oxygen consumption and average heart rates were lower while riding in the water. In other words, their cardiovascular systems were working more efficiently to do the same amount of exercise.Study author Dr. Martin Juneau is director of prevention at the Montreal Heart Institute in Canada. The institute’s EPIC center offers “Aquavelo” fitness classes and opens its water stationary bicycles up to members during open swim. Juneau says the bikes were so popular they had to start printing tickets to reserve workout times.Aqua bikes were originally created for rehab of knee injuries in athletes, Juneau says. But because water makes us virtually weightless, hydro-spinning is also used for obese or arthritic patients who want a low-impact workout.“Patients love it,” Juneau says. “They feel it’s easier, but when you look at the increase in (aerobic) capacity, it’s just as good as land training.”The researchers believe hydrostatic pressure (or the pressure of the water) on the body makes it easier for your system to return blood to the heart. This reduces the number of times your heart has to beat – lowering the average heart rate and amount of oxygen needed to sustain an intense workout.The study needs to be duplicated with more participants to confirm the results, Juneau says. Further research is also needed to see if the effects are the same for older and/or overweight cyclists.