BackgroundExercise is recommended as a core treatment for individuals with KOA. However, the optimal exercise program to promote long-term compliance for KOA patients is not clear. The aim of this study is to compare the effects of the combination exercise program (quadriceps strengthening exercises (QSE) plus Baduanjin qigong) versus QSE alone on older adults with knee osteoarthritis (KOA). MethodsA two-arm, quasi-experimental trial with repeated measurements was used. As a cluster randomized trial, participants from one community center were assigned to combination exercise group while participants from the other center were assigned to QSE group. We assessed pain intensity, physical function, self-efficacy, and HRQoL with standardized instruments at baseline, 3 and 6 months. Results87 participants with KOA who aged above 60 completed the study. Over the 6 months, There were significant time by group interaction effects on pain intensity (F = 44.419, p < 0.001), physical function (F = 46.904, p < 0.001) and self-efficacy (F = 49.754, p < 0.001), as well as in the physical component summary (F = 15.205, p < 0.001) and mental component summary of SF-12 (F = 19.205, p < 0.001), with the combination exercise group exhibiting significantly greater improvements in all outcomes than QSE group. ConclusionsCombination exercise treatment is more effective than QSE for relieving pain, increasing physical functioning, and improving self-efficacy, and quality of life in community-dwelling KOA older adults. Also, it could promote long-term compliance for KOA community patients.Trial registrationChinese Clinical Trails Registry number ChiCTR2000033387 (retrospectively registered). Registered 30 May 2020