This is the peer reviewed version of the following article: Bricca, A. , Wirth, W. , Juhl, C. B., Kemnitz, J. , Hunter, D. J., Kwoh, C. K., Eckstein, F. and Culvenor, A. G. (2019), Moderate Physical Activity and Prevention of Cartilage Loss in People With Knee Osteoarthritis: Data From the Osteoarthritis Initiative. Arthritis Care Res, 71: 218-226., which has been published in final form at https://doi.org/10.1002/acr.23791. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.