You say your dream summer fitness regimen would include short, high-intensity workouts that yield great strength and aerobic benefits with minimum post-exercise soreness. Oh, and you'd want to workout in a setting so cool and refreshing you'd hardly break a sweat. Just a fantasy?

Maybe not if you take plyometrics, a training method used by pro athletes to build explosive muscle power, and put it in an environment where you wouldn't ordinarily think to find it.

Done conventionally, plyometrics is taxing. Jumping repeatedly from a squatted position or from a cube tears up muscle fibers more than standard resistance training does, often leaving muscles complaining the loudest two to three days after a workout -- the time it takes those torn fibers to heal. That delayed-onset muscle soreness can be so extreme that most athletes practice plyometrics only during off-season, when they can afford the recovery days.

But an Ohio State University study published earlier this year in the Journal of Strength and Conditioning Research showed plyometrics done in a swimming pool yielded the same strength gains as the dry-land version but with much less post-workout pain. The eight-week study involved 32 physically active college-aged women; researchers say they'd expect to find the same results in men.

"Frankly, I was amazed at the results," said co-author Steven Devor, assistant professor of sport and exercise sciences at Ohio State and a fellow of the American College of Sports Medicine. "I thought we'd see less pain, but not equal strength gains."

In plyometrics, the muscle is contracting (that is, generating force) as it lengthens. For example, if you lie down and someone drops a medicine ball to you, as you catch it, your chest muscles are both contracting (to provide the strength to catch the ball) and lengthening. Plyometrics includes exercises for both upper and lower body, but aquatic plyometrics focuses on the legs and knees.

The workouts are shorter -- 20 to 30 minutes -- than a typical weight-training session because plyometrics makes your muscles work harder during each contraction than during muscle-shortening or neutral (isometric) contractions. Devor suggests three sets of five repetitions of each of the exercises. Plyometrics workouts are recommended only for people who have been strength training regularly for at least six months and are ready to step up their training. Players of sports like tennis, basketball and volleyball can use plyometrics to speed reaction time and provide more explosive power.

The challenge is getting access to a pool with the room for such movements (the ideal water depth, says Devor, is three to four feet) and a cube or similar object that can rest on the pool bottom for the jumping exercises. If you don't have a cube, he says, you can improvise by doing a series of long, two-legged jumps from a squatting position, but you won't get quite the same benefit.

"Not too many facilities are offering classes yet," Devor said. But, he added, "That's because nobody had studied [plyometrics] in water before."

-- John Briley

For less ouch and more spring, just add water.