Exercise in knee osteoarthritis - preliminary findings: Exercise-induced pain and health status differs between drop-outs and retainers

Background: Exercise effectiveness is related to adherence, compliance and drop-out. The aim of this study is to investigate if exercise-induced pain and health status are related to these outcomes during two exercise programs in knee osteoarthritis patients. Methods: Symptomatic knee osteoarthritis patients were randomly allocated to a walking or strengthening program (N=19/group). At baseline, patients were categorized according to their health status. Exercise adherence and compliance were calculated and drop-out rate was registered. For exercise-induced pain, patients rated their pain on an 11-point numeric rating scale (NRS) before and after each training session. Before each session the maximal perceived pain of the last 24 h (NRSmax24) was assessed. Patients rated their global self-perceived effect (GPE) on a 7-point ordinal scale after the intervention period. Results: 53% of the participants felt they improved after the program, 6 patients dropped out. The mean adherence and compliance rates were higher than .83 in both groups. Worse health and higher exercise-induced pain were seen in drop-outs. NRSmax24 during the first 3 weeks did not significantly increase compared to baseline, but correlated negatively with adherence during the homesessions (-.56, p < .05). Lower adherence during supervised sessions was significantly related with higher pre-exercise pain scores (rho = -.35, p < .05). Conclusion: Patients who drop-out show a worse health condition and higher exercise-induced pain levels compared to patients that retained the program. (C) 2015 Elsevier Inc. All rights reserved.