Floating in the absence of gravity, it took the crew two tries to piece together a mounting frame and a complex shock absorbing system designed to dampen foot-pounding vibrations that could jog -- and ruin -- sensitive science experiments.

Stringy black cables then were routed to special computer and electronic control boxes. Next, the frame and its "vibration isolation system" were painstakingly planted in a 20-inch (50-centimeter-) deep pit beneath the floor of the crew module.

And finally, the treadmill later this morning will be carefully mounted on the sunken base so the machines running surface will be perfectly flush with the floor.

Talk about a workout. But thats no big surprise.

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Space age treadmill

The treadmill "is not exactly like the common exercise equipment you would find in a sporting goods store," said NASA flight commentator Rob Navias.

There were guy wires to route, bungee cords to string, and vibration resistors to install -- all in the name of science.

Mission Atlantis
Look here for complete coverage of space shuttle mission STS-106.

"The goal is to create an exercise device that crew members can use any time of the day or night without imparting destructive vibrations on sensitive experiments," Navias said.

The high-tech treadmill is one of three pieces of exercise equipment the Atlantis crew is setting up for the stations first full-time tenants, who are due to arrive at the outpost in early November.

The new orbital health club also will include:

• An exercise bike strategically positioned over a porthole window in the floor of the new crew quarters. The window will enable exercising astronauts to watch the world below as they peddle around the planet once every 90 minutes.

• A "resistive exercise device," which is an aluminum framework that can be mounted on the treadmill so astronauts can to do squats, leg curls, calf raises, knee lifts and other calisthenics to exercise their legs, hips, trunk, shoulders, arms and wrists.

The exercise equipment is expected to go a long way toward helping station astronauts combat the potentially debilitating effect of lengthy stays in weightlessness.

Medical studies have shown that muscles atrophy, bone mass is lost and there is a general deconditioning of the cardiovascular, pulmonary and immune systems during long stays in space.

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Staying in shape

U.S. and Russian flight surgeons, consequently, have developed a rigorous exercise regime for the first resident station crew -- not to mention all those who will follow.

Six days a week, theyll pace themselves through hourlong workouts on the machines, doing both aerobic and resistive exercises to stay in shape.

Atlantis pilot Scott Altman carries supplies through the International Space Station this week in this Electronic Still Camera image beamed to Earth by the astronauts.

"Theyll have about two and a half hours to do this per day -- thats a long time," said NASA flight surgeon Phil Stepaniak. "Now some of that time is taken up in preparation and cleanup, but theyre overall exercise time will be a little over an hour a day."

The fitness center set-up came as the Atlantis crew headed into the home stretch of its space station outfitting mission.

The astronauts wrapped up electrical work at the outpost after flight directors decided to forgo any additional attempts to fix a bad battery in the crew module, leaving that work instead for the first full-time station residents.

Hooked up Tuesday, the newly installed battery subsequently failed to charge. The shuttle crew double-checked battery connections early Friday but were unable to pinpoint the problem.

With seven of eight batteries operating properly in the crew module, NASA officials say there is ample electrical power for the stations first resident crew.

Atlantis and its astronauts, meanwhile, will depart the station late Sunday. Landing at Kennedy Space Center now is slated for 3:56 a.m. Eastern Daylight Time (07:56 GMT) next Wednesday.