Eligibility criteria for participants were : ( 1 ) aged 50-75 years , ( 2 ) self-reported knee and/or hip OA , ( 3 ) self-reported inactivity ( 30 minutes of moderate PA , 5 times or less per week ) , ( 4 ) no face-to-face consultation with a health care provider other than general practitioners , for OA in the last 6 months , ( 5 ) ability to access the Internet weekly , and ( 6 ) no contra-indications to exercise without supervision .