Obesity is one of the greatest risk factors for osteoarthritis (OA) of knees. The National Health Assessment and Nutrition Examination Survey for 2009 through 2010 found that more than 65% of American adults are overweight (body mass index (BMI 25-29.9) and more than 35% of those obese (BMI greater than 30). With such large percentages of the population characterized as overweight, it is necessary to examine the wide array of health maladies that arise as a result of obesity.
Besides OA, obesity is also related to other musculoskeletal problems. Recent studies have shown adults who are overweight or obese, are significantly more likely to have disc degeneration in the spine than those with a normal BMI. The extent and severity of disc degeneration is dependent upon the elevation of one’s BMI. Weight gain, physical loading on the disc, and/or chronic low-grade inflammation of the disk due to fat cells may play a role in disc degeneration. Furthermore, obesity can increases the risk of lower back pain in causing excessive mechanical stress to all spinal structures including joints, discs, ligaments, and muscles.
Obese or overweight people are also two times more likely to develop carpal tunnel syndrome than people of average weight. Additionally, women are three times more likely to develop carpal tunnel than men. The pain, numbness, and tingling of the fingers, characteristic of carpal tunnel syndrome, result from compression of the median nerve. Compression occurs when the carpal tunnel becomes narrowed or when the tendons become enlarged. In obese people, adipose (fat) tissue can compress the median nerve. For example, when rising from a chair, obese people generally have to move their feet further under their body and use their arms to push out of the chair. This movement distributes weight upon the wrists, which may put additional pressure on the median nerve and rotator cuff tendons in the shoulders.
Adaptive movements described above as well as atherosclerosis—decreased blood flow to the rotator cuff tendons—which is common in obese people contribute to shoulder problems and the likeliness of trauma to the rotator cuff. In one study, the risk of rotator cuff tendinitis was 25% higher for overweight patients, 80 to 120% higher for moderately obese patients, and 300% higher for patients whose BMI was 35 or more, a score roughly 15 points higher than a healthy BMI.
It may be an oversimplification to say that excess weight causes such problems and that losing weight can resolve them since a causative relationship between musculoskeletal problems and excess weight can be difficult to establish. However, weight loss not only makes a substantial difference in most musculoskeletal problems, but also benefits cardiovascular fitness and overall health.