The deterioration of cartilage over time is also known as osteoarthritis. Moderate exercise may keep cartilage healthy, strengthen cartilage and decrease the risk of osteoarthritis. However, certain types of exercise may also accelerate the wearing down of cartilage and lead to development of osteoarthritis.
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Osteoarthritis is the most common form of arthritis, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases. It is caused by the progressive breakdown of cartilage within a joint. Cartilage is a hard material that lines the ends of bones and helps bones move smoothly, as well as provides cushioning. When cartilage becomes worn down, your bones may rub together and cause pain, stiffness, “cracking” and swelling of joints.
Exercise and Cartilage Wear
Exercise appears to be both beneficial and detrimental to cartilage. The Merck Manual notes that weight-bearing activities keep cartilage healthy by promoting the absorption of nutrients into cartilage, increasing the hydration of cartilage and releasing joint fluid into the joints and blood vessels. According to the Arthritis Foundation, regular, moderate exercise increases the strength of bones and muscles, flexibility and level of fitness, which in turn may strengthen the joint and protect it from damage. In fact, moderate exercise may even strengthen the cartilage itself. However, certain types of activities can also accelerate the progression of cartilage deterioration. Damage to the cartilage can cause cartilage cells to release inflammatory cells and enzymes that break down cartilage.
Activities that are repetitive, high-impact or involve twisting may accelerate the wearing down of cartilage, according to the University of Maryland Medical Center. Basketball, football, soccer and baseball pitching carry the greatest risk for damage. Other risk factors include: age older than 40; female gender; obesity; lack of exercise and occupations with repetitive movements.
A study published in 2005 in “Arthritis & Rheumatism” found that moderate exercise may improve the quality of cartilage in individuals at high risk for developing osteoarthritis. The researchers discovered that participants who engaged in moderate exercise three times a week for one hour experienced an increase in the glycosaminoglycan content of cartilage as well as an increase in level of activity. Glycosaminoglycan is a carbohydrate found in cartilage that contributes to its elastic and cushioning properties. This suggests that cartilage may respond to exercise the same way as muscle and bone.
While we do know that moderate exercise provides benefits for people with osteoarthritis, there is some question as to just how much exercise and what types will provide benefit without wearing out cartilage. One theory by physical therapist Doug Kelsey is that there is an “optimal amount of load and repetitions” in which the cartilage is strengthened. Stresses above this level may result in cartilage wear and stresses below this level may result in deterioration of cartilage. Ideally, this is achieved by keeping the load low and the number of repetitions high, such as water exercise, elliptical machines, stair climbers and bicycling.
While osteoarthritis is unavoidable to a certain degree, you should avoid activities that are repetitive, high-impact or involve twisting to slow the progression of cartilage damage. You should also lose weight if you are obese to decrease the amount of stress on the joints.