OBJECTIVE: To investigate whether muscle strength declines prior to or concurrent with incident knee pain in subjects with and without radiographic knee osteoarthritis (RKOA). DESIGN: Osteoarthritis Initiative participants with incident knee pain (occurrence of infrequent/frequent knee pain during the past 12 months at two consecutive follow-up time points [either years[Y] 3+4 or Y4+5]) were compared to controls (no incident knee pain) with 2-year changes in knee extensor strength during BL➔Y2 (prior) and Y2➔Y4 (concurrent). RESULTS: 202 knees (49% women; 40% RKOA) displayed incident pain, 439 did not (46% women; 23% RKOA). Women with RKOA displayed a significantly greater (p=0.04) reduction in knee extensor strength concurrent with incident pain compared with controls (mean -17.6 Newton vs +4.5Newton), but men did not. A similar trend was observed in women without RKOA - but this was not statistically significant (p=0.08). There was no significant relationship with change in extensor strength prior to incident pain (p≥0.43). CONCLUSION: These results suggest that, in women, incident knee pain is accompanied by a concurrent reduction in knee extensor strength, whereas loss in strength does not precede incident knee pain. The findings encourage interventional studies that attempt to attenuate a decline in extensor strength once knee symptoms occur.