Functional adaptation of knee cartilage in asymptomatic female novice runners compared to sedentary controls. A longitudinal analysis using delayed Gadolinium Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC)

Objective: To longitudinally estimate the change in glycosaminoglycan content of knee cartilage in asymptomatic untrained female novice runners participating in a Start To Run program (STR) compared to sedentary controls. Method: Nine females enrolling in a 10-week SIR and 10 sedentary controls participated voluntarily. Prior to and after the 10-week period, both groups were subjected to dGEMRIC imaging. dGEMRIC indices of knee cartilage were determined at baseline and for the change after the 10-week period in both groups. Based on a self-reported weekly log, physical activity change during the study was depicted as decreased, unchanged or increased. The Mann-Whitney U and Kruskal-Wallis tests were applied to test the hypotheses that dGEMRIC changes occurred between groups and according to physical activity changes respectively. Results: No significant differences were established between groups for dGEMRIC indices at baseline (P = 0.541). A significant positive change of the median dGEMRIC index in the runners group was demonstrated when compared to the controls [+11.66 ms (95% CI: -25.29, 44.43) vs -9.56 ms (95% CI: -29.55, 5.83), P = 0.006]. The change in dGEMRIC index differed significantly according to physical activity change (P = 0.014), showing an increase in dGEMRIC index with increasing physical activity. Conclusion: Since cartilage appears to positively respond to moderate running when compared to a sedentary lifestyle, this running scheme might be considered a valuable tool in osteoarthritis prevention strategies. Caution is warranted when applying these results to a wider population and to longer training periods. (C) 2010 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.