We know that regularly getting some exercise, no matter how little, can keep you alive longer. But new research out Monday suggests that even an hour’s worth of walking per week can help older adults with ailing knees avoid painful, isolating disabilities down the road. The researchers looked at data from an earlier project studying thousands of middle-aged and elderly Americans with knee osteoarthritis, the Osteoarthritis Initiative, which began in 2004. At the beginning of the project, the volunteers got a full medical check-up and answered questions about their lifestyle habits, then had their health periodically followed for up to 8 years. For the current study, the researchers looked at around 1,500 adults who had knee pain but no other disability at the beginning then tracked them over a four-year period.