This is an excerpt from Physiology of Exercise and Healthy Aging-2nd Edition by Albert W. Taylor & Michel J. Johnson.
By J. Thornton, MD, PhD, and G. Moatshe, MD, PhD
Physical Activity for Joint Health
Regular physical activity improves joint function through a variety of ways. Improvements in aerobic capacity, strength, and flexibility are associated with improvements in joint function, reductions in pain and swelling, and reductions in anxiety and depression levels (Minor and Kay 2009).
Physical activity is recommended for both prevention and management of osteoarthritis, the most common chronic disease in older people. Younger people can also manifest symptoms, though often as a secondary result of injury to the joint. Although many incorrectly assume that exercise causes OA, joint function and stability are improved with physical activity due to increases in muscle strength and neuromuscular function. For individuals with OA, exercise has been shown to reduce pain as well as improve overall well-being. Since there is a large variability of symptoms, in more severe cases physical activity should be carefully modified to ensure pain-free motion.
Individuals with symptomatic OA tend to be less active and less fit than their peers with joint disease. In addition, their range of motion may be restricted due to pain, stiffness, bony changes, and swelling. Gait abnormalities, pain, and stiffness may affect energy requirements and walking speed, and they should be considered when giving advice on physical activity.
The most immediate benefit of physical activity for OA (table 7.4) is the reduction in health risks due to inactivity. Physical activity that incorporates moderate joint loading is beneficial in both prevention and treatment of OA (Manninen et al. 2001). Joint stability is increased with physical activity due to improvements in muscle strength and neuromuscular function. Careful physical training can also reduce joint cartilage degeneration (Roos and Dahlberg 2005). In patients with OA, aerobic exercise reduces pain via increased endorphin levels and is associated with weight loss, which can reduce total load on the joint. Running, through its association with lower body mass index (BMI), reduces OA and hip replacement risk (Williams 2013), although in advanced cases of OA it may cause an increase in pain, and physical activity may need to be modified.
Dynamic strength training beginning with body weight is advised. Type of physical activity is also based on the joint in question. For knee OA, strength training of the quadriceps and gluteus muscles may be key, while hip flexibility is also important (Roos 2010). Mind–body training programs (e.g., yoga, tai chi), when performed routinely, are promising approaches for reducing pain and improving physical function and quality of life in knee OA (Brousseau et al. 2017a,b,c; Lauche et al. 2013).