Equestrian Susan Childers gets a workout on the Quadmill at the downtown Seattle Athletic Club under the watchful eye of fitness director Aron Branam.

That's when the platform began rolling and swooping up and down and side to side. At first, it felt as if I were standing in a small fishing boat, riding out a roiling wake. Then, I could see why skiers use the machine to prepare for taking on moguls.

I kept my knees bent as the platform rolled up and straightened them as it descended to the bottom of its sweep. I did as Branam advised, keeping my head and upper body still and my hands just off the rails so my core, glutes and legs could do and feel the maximum effect.

It was a fun and flowing ride, especially when I caught the rhythm. It seemed easy, too, which surprised me because Branam said two minutes is about the maximum time most club-users spend on the machine at one turn.

Yet, while it initially felt like a no-impact ride, it stealthily delivered considerable impact to the targeted areas. The gentle warmth in my leg and ab muscles slowly gave way to a creeping burn.

I did a ski stance for 30 seconds. Then I turned sideways, facing one of the rails and allowing it to rock me sideways. I turned around and worked the other side for the same period. This seemed a cross between surfing and the side-to-side shuffling I'd do while playing defense or preparing for a return in handball or tennis. We finished the two-minute workout with 30 seconds more in a snowboarding pose. This targeted my knees and hamstrings.

Two minutes was enough. Although never working to a sweat, my legs felt rubbery and my abs tweaked by the time I walked out of the club. As the day wore on, my quads and hamstrings were a bit sore, and that lasted another day.

The Quadmill was invented and is being produced by a Moses Lake company called Cascade Fitness Technologies. The Sonics use the device. So do the Navy SEALS and U.S. Olympic Ski Team. So far, it can also be found at the Seattle Athletic Club, Bellevue Place Club and Bellingham Athletic Club.

Dwight Daub, player-development coach for the Sonics, says the device is an integral part of the team's training and rehabilitation program. When a player is coming off a knee operation or has tendinitis, he uses the machine because it is no-impact but challenging. It also challenges muscles used while playing defense or rebounding.

Branam uses it in his ski-season prep class. That's exactly what gave co-inventor Dr. Kevin Creelman the idea a decade ago.

While planning his annual ski vacation and pondering the annual frustration of being incredibly sore for the first three days of every week-long ski excursion, Creelman began thinking of ways to better train his body for the rigors. He doodled movements on a prescription pad and eventually connected with a cousin, Terry Jacobs, who operated an air-bag parts plant in Moses Lake and had acumen for building things.

The Quadmill hit the market a few years ago, but the updated version has begun circulating this year.

The machine takes advantage of eccentric training, which engages muscles while they are lengthened rather than shortened, as is the case with normal weight-bearing motions. It emphasizes leg, core and back muscles you use in a crouch. Downhill skiing, for instance, uses eccentric muscle activity in the lower body. Running and jumping sports use a combination of concentric and eccentric.

Says Creelman, a doctor in Kodiak, Alaska: "The theory is that a key element in sports conditioning and injury prevention is the ability to absorb the downward forces on the legs and low back time after time by regular eccentric exercise of those muscles."

He said eccentric conditioning had a "bad rap" over the years because it was associated with DOMS, or delayed onset muscle soreness, that some felt represented injury and required periods of rest.

"It now is known that you can resume exercise even when this soreness is present and continue to make gains," he says, "and that what they thought was injury and inflammation is really a unique adaptation of the muscle structure in response to eccentric exercise."

There seems to be at least a few studies that bear him out, and Daub says he has no evidence of the DOMS syndrome.

Richard Seven is a Pacific Northwest magazine staff writer. Greg Gilbert is a Seattle Times staff photographer.

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