Effects of exercise intervention on knee morphology in middle-aged women: a longitudinal analysis using magnetic resonance imaging.

INTRODUCTION

Epidemiological studies show a positive relationship between physical activity and cartilage volume, suggesting that exercise may protect against osteoarthritis. Cross-sectional experimental studies, however, have failed to show significant differences in knee cartilage morphology between athletes and nonathletic controls. The aim of the study was to test the hypothesis that knee cartilage morphology, specifically regional cartilage thickness and global subchondral bone area, is modified in sedentary, untrained adult women who increased their physical fitness during a 3-month supervised exercise intervention.

MATERIALS AND METHODS

Thirty-eight untrained women, aged 45-55 years, were randomly assigned to: endurance training (n = 18), strength training (n = 15) and autogenic training (control group, n = 5). Patellar and femorotibial knee cartilage morphology was determined before and after the 3-month supervised training intervention, using magnetic resonance imaging and state-of-the-art image analysis.

RESULTS

Whereas the endurance training group showed a significant increase in cardiorespiratory fitness and the strength training group a significant increase in the maximal voluntary isometric contraction force of the leg, this study did not show significant differences in knee cartilage thickness and volume, subchondral bone area or regional cartilage thickness between baseline and follow-up acquisitions within any intervention group.

DISCUSSION

This randomized longitudinal study provides no evidence that a 3-month exercise intervention in untrained middle-aged women can significantly alter knee joint morphology. Longitudinal evidence supporting that a training program, successful in increasing physical fitness, can also induce functional adaptation of articular tissues and may protect against knee osteoarthritis, remains to be presented.