Lifelong moderate running training increases the incidence and severity of osteoarthritis in the knee joint of C57BL mice

Abstract

Background: Inbred C57BL made mice express a high incidence of spontaneous osteoarthritis of the knee joint at the age of 18 months. We used this strain of mice to find out the effects of life-long, moderate running exercise on the health of articular cartilage and the incidence of osteoarthritis. Methods: Male mice (294) were divided into controls and runners. The runners were trained daily between 2 and 18 months of age. The speed was 13.3 m/min and the distance on a flatbelt treadmill was 1,000 m/day. The mice were sacrificed at the ages of 2, 6, 10, 14, and 18 months. The Knee joints were sectioned in frontal direction and the osteoarthritic changes were graded using a conventional light microscope. The reproducibility of the grading method was tested by calculating extended k-coefficient for the results of six researchers. Results: The incidence of osteoarthritis at the age of 18 months increased from 72% in controls to 88% in runners in the medial tibial condyles (PConclusion: According to our results, the moderate, long-lasting running exercise accelerates the development of osteoarthritis in the knee joints of C57BL mice.