Pain and fatigue are longitudinally and bi-directionally associated with more sedentary time and less standing time in rheumatoid arthritis. - O'Brien CM; Ntoumanis N; Duda JL; Kitas GD; Veldhuijzen van Zanten JJCS; Metsios GS; Fenton SAM (Rheumatology (Oxford, England), 2021)