['It has been reported that osteoarthritis can occur in hamsters. The present study was undertaken to determine the effects of exercise on the composition of articular cartilage and synovial fluid and on the development of cartilage degeneration in these animals.', 'Young (2.5-month-old) group-housed hamsters were compared with 5.5-month-old hamsters that had undergone 3 months of daily wheel running exercise (6-12 km/day) or 3 months of sedentary, individually housed living. The condition of the femoral condyles was determined by scanning electron microscopy in 12 exercising hamsters, 12 sedentary hamsters, and 6 of the young controls. The content of proteoglycan, hyaluronic acid, hydroxyproline, and proline in synovial fluid and patellar cartilage was measured.', 'By scanning electron microscopy, the femoral articular cartilage was smooth and undulating in young controls and older exercising hamsters. In contrast, the femoral condyles were fibrillated in all 12 of the sedentary hamsters. There was no difference in the patellar cartilage collagen content between the 3 groups, but proteoglycan content and synthesis were lower in the patellar cartilage of the sedentary group. Synovial fluid volume was also decreased in the sedentary group compared with the young controls or the older exercising hamsters.'] Does exercise protect against articular cartilage degeneration in the hamster?