Stephen Snitzky's feet have touched the ground for the first time since August. The healthy, physically fit man who agreed to help science by remaining in bed or suspended in a body-length harness for 12 weeks took his first shaky step Monday.

The Cleveland Clinic researchers conducting the study of bone loss and muscle atrophy hope his work will someday help astronauts.

Now, Snitzky, 31, of suburban Euclid, will work to regain his strength while spending at least four days in a hotel room on the clinic's campus. He'll return to his job, as manager of an H&R Block, in January.

During the study, Snitzky read 29 books and watched 25 movies. He estimated that he played about 1,000 games of solitaire.

When in bed, he had to keep his head slightly lower than his feet, which could never touch the ground.

"It's a weird feeling," Snitzky said when his SpongeBob SquarePants slippers hit the floor. With help, Snitzky walked out of his room, into the hallway and back several times.

Snitzky was one of the first two men to participate in the Cleveland Clinic's Center for Space Medicine study, which is funded by NASA and the National Space Biomedical Research Institute. Similar studies are being done at the University of Texas Medical Branch in Galveston, Texas.

For 20 minutes a day, five days a week, participants float in a weightlessness device that involves a suspension cradle, rock-climbing gear and cords. Some in the study exercise on a vertical treadmill (search) while in simulated weightlessness. Others, such as Snitzky, do not. Researchers will compare body responses.

The other man in the initial Cleveland study did not want to be identified.

Peter Cavanagh (search), chairman of the clinic's biomedical engineering department, said he is searching for 22 more people to participate in the study. Prospective participants must be nonsmokers between the ages of 21 and 50 and free of orthopedic injuries, bone disease and vascular disease.

Researchers will watch Snitzky closely for the rest of the week, and then he will receive eight weeks of physical therapy, Cavanagh said. Snitzky will likely have some joint pain.