Adaptation of rat knee meniscus to prolonged exercise

The morphological and biochemical adaptations of knee meniscus to prolonged exercise were studied. Female Sprague-Dawley rats maintained under controlled environmental conditions were randomly assigned to either an endurance-trained or a sedentary group. Training consisted of a progressive exercise protocol on a motor-driven treadmill, 5 days/wk for 12 wk. Knee lateral menisci were obtained from anesthetized rats and used for morphological and biochemical analyses. Gastrocnemius succinate dehydrogenase increased 65% in the endurance-trained group, as evidence for a training effect. In the trained group, collagen, proteoglycan, and calcium concentrations increased significantly in the posterior region of the lateral meniscus. In contrast, no significant changes were found in the anterior region of the lateral meniscus. The region-specific changes in meniscal concentrations of calcium and matrix macromolecules in response to prolonged exercise are consistent with the distinctly different mechanical properties and functional roles of the anterior and posterior regions of the rat knee meniscus.