Abstract
OBJECTIVE: This study investigated the effects of a high-impact exercise regimen compared with a reference group on systemic cytokine levels in patients with mild knee osteoarthritis (OA). Furthermore, associations between cytokines and magnetic resonance imaging (MRI) transverse relaxation time (T2) mapping and metabolic equivalent task hours (MET-hours) during leisure-time physical activity (LTPA) were assessed. METHOD: In this secondary analysis, 73 postmenopausal women aged 50-65 years with mild knee OA were randomized to a 12-month high-impact aerobic/step aerobics training group (n = 35) or a non-training reference group (n = 38). The serum cytokine levels, including interleukin-1 alpha (IL-1α), IL-2, IL-4, IL-5, IL-6, IL-10, IL-13, IL-17, interferon-gamma (IFN-γ), and tumor necrosis factor alpha (TNF-α), were determined via multiplex cytokine assays. The cartilage structure of the medial tibial condyle was assessed by MRI T2 mapping. The primary outcome was between-group differences in cytokine level changes. RESULTS: After a 12-month follow-up, no significant differences in cytokine level changes were found between the groups. In the intervention group, 12-month changes in TNF-α levels were associated with changes in medial tibial condyle T2. In the reference group, 12-month changes in IL-10 levels were associated with changes in medial tibial condyle T2 and the number of weekly LTPA MET-hours. CONCLUSION: A progressive high-impact exercise regimen did not affect systemic cytokine levels compared to the reference group and could therefore offer a possible mode of exercise for postmenopausal women with mild knee OA. TRIAL REGISTRATION NUMBER: ISRCTN58314639.