Effect of exercise on osteoarthritis

The popularity of jogging among the population of many countries in the world has recently attracted attention to running for long distances as a factor in the risk of developing osteoarthritis. Retrospective and prospective studies have shown that the clinical and radiological criteria for osteoarthritis in middle distance runners and marathon runners are not detected more often than in people who do not run. However, due to the fact that the design of most of these studies has a number of shortcomings (incorrect statistical analysis, incorrect methods of diagnosis or assessment of osteoarthritis, etc.), their results raise doubts. NE Lane and coauthors (1986, 1987,1993) tried to correct the mistakes of previous researchers. For 9 years, they studied the radiographic signs of osteoarthritis in runners-lovers of advanced age (mean age 65 years). It was found that in this category of persons the incidence of osteoarthritis (radiologically confirmed) did not exceed that in a group of persons of the same age who are not addicted to running. Although in the group of amateur runners, subchondral sclerosis was more often recorded in women, and in both sexes - osteophytes were more often found on X-rays, nevertheless the authors concluded that unprofessional exercise in athletics is not a risk factor for osteoarthritis. Thus, the data presented indicate that in individuals with "healthy" joints, long-distance running is not the cause of cartilage degeneration and the development of osteoarthritis.

Studies of biomechanics of osteoarthritis on animal models confirm the above conclusion. PM Newton and coauthors (1997) investigated beagles who were trained to run at a speed of 3.3 km / h for 75 minutes a day for 5 days a week. Each dog carried an additional "exogenous" load of 11.5 kg (130% of body weight). The control group consisted of adult hounds, which were not trained and did not use additional load. 52 weeks after the start of the training, a histological examination of articular cartilage, menisci and ligaments was carried out. It turned out that the applied load level did not cause degenerative changes in the joint tissues in dogs. There was no difference between the biomechanical properties of cartilage in trained and untrained dogs.

In another study, young hounds (with an immature skeleton) were trained in a medium difficulty program (4 km / h on a treadmill with a 15 ° slope) for 15 weeks. The authors discovered a thickening of the cartilage and increased synthesis of proteoglycans compared to the control (untrained) group of animals. However, most proteoglycans in the cartilage of trained animals lost their ability to aggregate with hyaluronic acid and contained more chondroitin-6-sulfates. The authors of the study suggested that such a level of loading accelerates the maturation of matrix deposits in the articular cartilage of animals.

In the study, conducted with the participation of young hounds, the training program was somewhat complicated: 20 km per day for 15 weeks. Such a load caused a decrease in collagen concentration, an increase in the water content, a decrease in the ratio of chondroitin-6 and chondroitin-4-sulfates in the articular cartilage of the lateral condyles of the femurs. The increase in the distance to 40 km per day and the duration of training up to 52 weeks was accompanied by a decrease in the content of proteoglycans in the cartilage VKM. The most pronounced loss of glycosaminoglycans was noted at the apex of the condyles of the femurs, especially in the surface zone of the cartilage.

C Little and co-authors (1997) demonstrated that prolonged intense training can induce changes in the metabolism of proteoglycans in the wrist joints in horses. In the framework of this study, the authors studied the effect of moderate or high training loads on the synthesis and degradation of large aggregated proteoglycans (aggrecan) and two small dermatan sulfate-containing proteoglycans (decorin and biglikan). Explants of articular cartilage were taken from the three sections of the third wrist bone, which account for the greatest load and which are most often injured in sports horses. Twelve horses aged 3 to 5 years without clinical or radiographic signs of the pathology of the middle wrist were included in the study. The training program included running at a speed of 6 m / s 2000 m 3 days a week with an increase in the distance to 4000 m by the end of the 8th week of the study. Then all the animals were divided into two groups - the animals of group A continued training in the previous regime, while in the group B animals the training regime was strengthened (running at a speed of 8 m / s at a distance of 4000 m 4 days a week for 17 weeks). After 16 weeks after the end of training, material was taken from certain parts of the third wrist bone from both sides.

In the histological study of the cartilage of animals of both groups, depression of its surface areas and destruction of calcified cartilage and "wavy border" were detected only in the region of the dorsal radial condyle of the third wrist bone. There was no significant difference between the detected histological changes between groups A and B. In the culture of explants of articular cartilage, a greater number of proteoglycans from the cartilage of the dorsal radial condyle was released to the animals in group B than in the animals of group A, which indicates a higher level of catabolism in group B. The incorporation of ³⁵ S into proteoglycans was less pronounced in the explants obtained from animals of group B; At the same time, the animals of this group observed an increase in the biosynthesis of the decorin, no changes in the intensity of the bi-synthesis of biglucan were detected. Thus, the results obtained indicate that prolonged intensive training of horses induces inhibition of the synthesis of aggrecan and an increase in the synthesis of dermatan sulfate-containing proteoglycans.

The functional role of decortin in connective tissue in general and in cartilage, in particular, remains a subject for research. It is believed that decore plays a central role in the organization of collagen macromolecules, cell proliferation and modulation of the activity of growth factors (eg, TGF-P). Addition of the decorin to the collagen gel caused the deposition of more homogeneous thin collagen fibrils than in its absence. In the cervical tissue after delivery, the destruction of the collagen network correlated with the increased level of the decorin. Thus, the decorin, most likely, plays the role of a "conductor" in the processes of repair and remodeling of connective tissue.

An increase in the synthesis of chondrocyte chondrocytes in articular cartilage of horses against a background of high dynamic loads can be interpreted as follows: the released from the damaged chondrocytes in response to mechanical overload, decorin acts as a messenger. This hypothesis is supported by in vitro and in vivo studies, which demonstrated an increased production of decore by chondrocytes subjected to a physiological mechanical load. T. N. V.V. Korver and co-authors (1992) reported that cyclic loading, in vitro, applied for 7 days, increases the synthesis of decorin in explants of articular cartilage by a factor of 3. Similar results were obtained by NA Vissen and co-authors (1994) who used explants of mature and immature articular cartilage. In a model of early (hypertrophic) osteoarthritis induced in dogs by crossing the anterior cruciate ligament, GS Dourado et al. (1996) observed an increase in the level of mRNA of biglikan, decorin and fibromodulin in the cartilage of destabilized joints.

[1], [2], [3], [4], [5], [6], [7], [8]