Objective physical activity measurement in the osteoarthritis initiative: Are guidelines being met?

Dorothy D. Dunlop, Jing Song, Pamela A. Semanik, Rowland W. Chang, Leena Sharma, Joan M. Bathon, Charles B. Eaton, Marc C. Hochberg, Rebecca D. Jackson, C. Kent Kwoh, W. Jerry Mysiw, Michael C. Nevitt, Jennifer M. Hootman