In some ways, plyometrics resembles playground fun more than hardcore training.

Plyometrics – hops, jumps, skips and other exercises designed to increase explosiveness, balance and agility – can be anything from jumping rope to complicated footwork drills.

“Plyos are fun,” says Jim Whittaker, a sports physiologist, cycling coach and competitive cyclist who prescribes plyometrics for his clients, athletes – and himself. “I call ’em frogs, doing frogs, and they really are fun.”

And while they’re everywhere in competitive sports – you’d be hard-pressed to find an NBA, NFL or major-college strength-and-conditioning program that doesn’t include at least some form of plyometric exercise – plyometrics aren’t necessarily on just every recreational athlete’s list.

“Would they help an athlete in any sport? I’d say, yes,” Whittaker said. “There are certain sports, like volleyball or basketball, where explosiveness is fundamental. In cycling, for instance, plyos will help you in a sprint, but if you don’t have the endurance to get to the finish line, it won’t help.

“But the speed and power sports, like volleyball, basketball – anytime you run, like in football, baseball, track and field – will it help you? Hell, yeah.”

What are plyometrics?

Said originally to have been a product of the eastern bloc sports empire, plyometrics uses the rubber-band properties of muscle to store and release energy.

It’s stretching the muscle, loading it with weight, then firing. Since a contracted muscle has stored energy, the recoil of that force increases the stress put on that muscle. In other words, it’s like pulling back a rubber band and firing it.

“Muscles are elastic,” Whittaker said. “If you store energy then release it, it gives you more jump and more power.”

The exercises themselves can range from skipping to the exaggerated bounding frequently seen among track-and-field athletes to weighted depth jumps, in which an athlete wearing a weighted vest drops off a box, compresses, then jumps back up.

Whittaker offers a word of caution, however.

“Your conditioning has to be appropriate,” he said. “Plyometrics can be as benign as a long jump or as difficult as weighted jumped with a weight belt. For some, you need to have a good level of conditioning. They’re dynamic and explosive movements. If you do some of the things a hardcore track athlete does, if you’re not prepared for it, you can definitely injure yourself.”

Whittaker offers himself as an example.

Every year, he says, he tweaks a calf muscle after plyometric work, even if he has prepared for it.

“That tells me just how much force is being generated,” he said.

‘Everybody benefits’

Plyometrics is part of an 18-week, six session “sports acceleration” program at TherapyWorks, 1112 West Sixth.

The program has four goals: to improve speed through increased stride length and frequency; improve anaerobic endurance; improve sprinting biomechanics; and improve body composition (in part through plyometrics) and enhance an athlete’s mental capacity.

“If you took away the plyometrics, you’d definitely take away half the program as far as the improvements we see,” said James Findley, a TherapyWorks acceleration specialist.

Findley said participants on average see a three-inch improvement in vertical leaps.

The program has different levels and protocols based on fitness and sport, but Findley says athletes of all sports at all levels could improve.

“Everybody benefits from it,” he said. “Everybody from professional Arena Football players to women’s football players to marathon runners to soccer players. Even marathon runners : their improvement is keyed to the treadmill work, but the plyometrics don’t hurt. Basically, it makes you more agile.”

Jumps for everyone

Whittaker thinks just about everybody – from weekend warrior to age-group pack fill – could incorporate some form of plyometrics into his or her training.

“I think especially for the masters-level athlete, the 30- to 35-year-olds, I think they’re really very underutilized,” Whittaker said. “But at the same time, you have to be very well conditioned before doing them.”

Whittaker sounds another cautionary note: Plyometrics is not like strength training.

Often strength training is performed until fatigue sets in. Plyometrics is not.

“It’s like sprinting. Quality is paramount,” Whittaker said. “You never want to do it to exhaustion or failure. Once you can’t do it perfectly and powerfully, you stop.

“I’d do plyos twice a week for 20 minutes, and I’d never leave there and feel trashed. But I could tell when I went to sprint, I had that little extra in the tank.”