Knee osteoarthritis (OA) is a chronic condition that causes pain and disability in older adults. Currently, there are no curative treatments that reverse knee OA. However, exercise has been demonstrated to slow the progression of knee OA, reduce pain, and improve physical functioning. The mechanisms through which exercise improves pain in this population are unclear. Prior research in healthy adults suggests that physical activity, including acute bouts of exercise, is associated with improvements in central pain processing. We wanted to explore the relationships of free-living physical activity with somatosensory function and the acute effects of walking exercise in older adults with knee OA. Physical activity was measured with a thigh-mounted accelerometer worn for 1 week. Participants underwent pain pressure threshold (PPT) testing (algometer placed 2cm proximal to the superior edge of the patella) before and immediately after walking for 6-minutes at a fast pace. Participants (N=46) had a mean age of 73.5 (SD=6.3) years, 80.4% were women, and 17.4% self-identified as racial/ethnic minority. Mean pre-exercise PPT was significantly higher in men (6.6±1.9kg) than in women (4.7±2.0kg, P=0.01). There were no relationships between accelerometer measured physical activity and PPT in men or women (p>0.05 for all comparisons). For example, the correlation between average daily step count and pre-exercise PPT was -0.08 in women. When comparing PPT before versus after walking 6 minutes, women exhibited exercise-induced hypoalgesia (pre-post within person mean difference=-0.35kg, P=0.01), but this effect was not observed in men (mean difference=0.23kg, P=0.65). Preliminary results suggest that moderate-to-vigorous walking exercise can induce hypoalgesia in older women with knee OA, but free-living walking and other measures of physical activity were not associated with PPT. In the future, we plan to enroll additional participants and examine changes in PPT and other measures of somatosensory function after a multicomponent exercise intervention.