It’s accepted wisdom that running with ruin your knees, degenerating kneecap cartilage and reducing its shock-absorbing capacity. Yet a recent study suggests runners might not be prone to degenerating knees after all, the New York Times reports. In the 2008 study, a team from Stanford University followed distance runners over 20 years, starting in 1984, when most were in their 50s or 60s. Among the group, 6.7 per cent of the runners had severely arthritic knees, while 10 per cent of the control group did. After 20 years, the runners’ knees actually improved: only 20 per cent showed arthritic changes, versus 32 per cent of the control group’s knees. About two per cent of the runners’ knees were severely arthritic, compared to almost 10 per cent in the control group. Running could shield against arthritis, it seems, partly because the knee develops a motion groove. Another Stanford study, published in February, showed that walking or running can “condition” the cartilage to the load, making it accustomed to the movements. But if it’s disturbed, generally by an injury, loading mechanisms shift and a degenerative pathway opens.