Author(s): VESANTO, J., KONOLA, V.M., MULTANEN, J., KALAJA, M., HAUTALA, A.J., VASANKARI, T., PARKKARI, J., NIEMINEN, M.T., CASULA, V., KAUTIAINEN, H., PEUNA, A., HEINONEN, A., Institution: UNIVERSITY OF JYVÄSKYLÄ, Country: FINLAND, Abstract-ID: 2167

INTRODUCTION:
Knee osteoarthritis (KOA) is associated with physical function limitations, including muscle weakness, which is also a possible modifiable risk factor for falls. Exercise is one of the key components of management in KOA, with potential to relieve pain and improve physical function. Exercise does not appear to be harmful to articular cartilage, but the effects of moderate intensive exercise on cartilage structure are not well known. Therefore, the objective of this study was to investigate the effects of combined resistance and moderate-impact training on tibiofemoral cartilage structure and lower limb muscle strength in postmenopausal women with mild KOA.
METHODS:
Postmenopausal women (n=409, aged 55-75 years) were recruited based on a newspaper advertisement and a phone interview. According to the inclusion and exclusion criteria, 103 volunteer postmenopausal women with radiologically confirmed grade 1 or 2 KOA, following to the Kellgren-Lawrence grading system, participated in the baseline measurements. After that they were randomly assigned to a multicomponent exercise group (n=51) and a home exercise group (n=52). The 8-month intervention included supervised progressive resistance and moderate-impact step aerobics training three times a week alternating with two-week periods. The home exercise group's training was standard rehabilitative training for KOA three times a week. Tibiofemoral articular cartilage was evaluated using quantitative magnetic resonance imaging. The structure of cartilage was assessed using gray-level co-occurrence matrix texture analysis of T2 relaxation time maps, sensitive to the collagen network arrangement and tissue hydration. Maximal isometric knee extension and flexion strength were measured. Measurements were performed at baseline and after the 8-month intervention.
RESULTS:
During the 8-month intervention, training compliance was 72% and mean training frequency was 2.2 (SD 0.6) times per week in the multicomponent exercise group, and 44% and 1.3 (SD 1.0) in the home exercise group. After the intervention, there were no statistically significant intergroup differences in the tibiofemoral cartilage structure between the multicomponent exercise group (n=47) and the home exercise group (n=43). The mean maximal isometric knee extension strength improved 15% (49 N, 95% CI: 30 to 68) and flexion strength improved 12% (22 N, 95% CI: 9 to 35) significantly more in the multicomponent exercise group compared to the home exercise group.
CONCLUSION:
Progressive resistance and moderate-impact training did not induce harmful changes in tibiofemoral cartilage microstructure, as reflected by texture analysis, in postmenopausal women with mild KOA. However, this type of moderate intensive resistance and impact training can promote lower limb muscle strength, which is important in maintaining physical function and activity in everyday life with KOA, and in preventing the risk of falls and resulting fractures in ageing.