The water workout trend health experts are gushing over

Whether you call it water running, aqua jogging or hydrotherapy, you can't beat a workout in water for an array of health benefits, many experts say. Everyone from pro athletes to stroke survivors are benefitting from aquatic exercise that combines walking or running against the natural resistance of the water to help build strength and endurance.

Running and walking in water is an excellent form of physical therapy for people rehabilitating from hip, knee and back injuries and surgeries. It's also an easy-on-the joints form of exercise for seniors and others who suffer from arthritis, and a recent study shows it can speed recovery from stroke faster than using a traditional treadmill.

It's just an all-around good aerobic conditioner for athletes, too, sports medicine expert Dr. Naresh Rao, told CBS News. Rao is the Olympic Team USA Water Polo Physician for the 2016 Summer Games.

"We've been using hydrotherapy to help decrease any sort of gravity that can affect joint function," said Rao, who is also with the department of family medicine at Plainview Hospital in Plainview, New York. "I personally prescribe it for knee issues and low back issues."

Hydrotherapy uses a water-friendly treadmill that can be placed in a pool. Another method involves a specially designed treadmill tank.

Matt Johnson, a physical therapist at St. Luke's Hospital in Bethlehem, Pennsylvania, told CBS News that the tank is basically a freestanding tub, about six feet long by three feet wide, with a motorized belt. The water height can be adjusted to the patient's abilities. The buoyancy of the water helps someone who's been injured to walk and run a little sooner than they'd be able to do on dry ground, he explained.

"In water, we can teach them sooner. They can really work on their gait, walk without pain, do exercises in water that you wouldn't be able to do on land," said Johnson.

He uses a HydroTrack Underwater Treadmill System – professional sports teams including the New York Yankees and the Miami Dolphins, have used it, too. The nice thing about it, said Johnson, is that people can step right into the tank at ground level and then the water fills up around them. It works like a lock on a canal, he said. So, even older patients with limited mobility and balance don't have to negotiate getting down into a pool.

Johnson starts off recuperating athletes and patients in water somewhere between waist and chest height. The treadmill speed can be set anywhere from 0.3 to 7.1 miles per hour depending on how much resistance a person can handle.

"At waist height, it's at about 50 percent of body weight. At chest height, it's about 30 percent of body weight," Johnson said, noting, for example, that a person with an injured knee who weighs 100 pounds who is running in waist-high water would only feel like 50 pounds on the bad knee.

"Taking some of that pressure off the knee helps them tolerate that knee injury longer," said Johnson.

A recent study in the American Journal of Physical Medicine and Rehabilitation showed that water workouts might benefit stroke survivors. Researchers asked 21 patients who'd had a stroke within the past two months to undergo two treadmill exercise tests – one submerged in water and one on a regular treadmill. They gradually increased walking speed and slope over time until the patients couldn't go any further. Walking on the underwater treadmill produced better measures when it came to maximal oxygen consumption (VO2max), a reflection of heart and lung function during exercise, and metabolic equivalents, a measure of energy use.

"The study proposes a different, very innovative approach" to rehabilitation after stroke, said Dr. Gisele Wolf-Klein, director of geriatric education at Northwell Health in Great Neck, New York.

Wolfe-Klein told CBS News she has tried water workouts and said you don't even feel like you break a sweat even if your heart rate is up. "It's a very pleasant way of achieving exactly what you're trying to do – allowing a cardio-respiratory response," Wolfe-Klein told CBS News.

She noted that medicine's veterinary counterparts have been using water therapy for years with injured racehorses.

Budd Coates, training director at Runner's World magazine, said runners don't just plunge into water therapy when they're injured; it's a great conditioning method for healthy athletes, too. Some recreational swimming pools and homeowners with backyard pools have manual treadmills that are water-safe and can be plunked right in the water.

An alternative to a water treadmill: Some pool companies will install a water flow system you can work out against.

"It creates a water force and helps keep you jogging in place," said Coates.

For those without access to a water treadmill, you can purchase a foam vest specifically designed for water jogging or use foam barbells to help keep you afloat. Some pools may loan them out, too.

Or, Coates suggested, just try it freeform with waist- or chest-high water to start. If you have trouble getting in out of a recreational pool, look for one that has a slanting beach-style entry into the water, or one with a robotic chair lift. Ask a pool lifeguard or certified swim instructor to help you.

If running's not your thing, but the water looks inviting, Coates said there are also spin bikes that can be used underwater.

Coates said the beauty of water running (or even walking) is that it's great for any age and any level of ability, from elderly stroke survivors to Olympic athletes.

Galen Rupp, the 2016 Rio Olympics men's marathon bronze medalist, relies on it as part of his training.

"He and some of the other guys on the Nike team, it's well known they take advantage of the anti-gravity treadmill and the aqua track," Coates said.