Knee problems
Obesity Is a Major Factor Contributing to Knee Problems
During an adult body’s development, the bone structure, muscle mass and cartilage and tendon strength become tailored to your genetic make-up, body type and build. When a person becomes overweight or obese, this generally happens at a much faster rate than it takes for a body to develop. (1) It should come as no surprise then, that accelerated increases to body-mass from a relatively fast accumulation of body-fat make it difficult for your body to cope with this on a number of levels. (2) Think of it this way: your body is tailor-made by your development and genetic factors to bear a certain load. In a way, your body mass index (BMI) is a measure of this. An adult person’s BMI is a number calculated from your height (largely influenced by genetics) and your weight (largely influenced by environment and development). The higher your BMI, the closer you are to the overweight/obese spectrum. The lower your BMI, the closer you are to the underweight spectrum. Ideally, an adult person’s BMI should be hovering somewhere in the 18-24 range. (3)
Bone structure in knees damaged through obesity
It should come as no surprise then, that if you are overweight or obese, parts of your bone structure might suffer. Studies actually show that visceral fat, which is undesirable fat that builds up around the abdomen when a person becomes overweight or obese, has negative effects on bone structure and strength. (4) This has been shown in many studies conducted by research teams across the world - the more body-fat your bone structure has to carry, the more likely you are to experience all sorts of pains, aches and even long-term debilitating diseases and conditions in various parts of your body. (5) The knees are no exception: the knees act as a sort of shock absorber for your body and don’t only exist to allow your legs to bend and give you the ability to walk upright, but the cartilage, muscles and bones in your knees, thighs, pelvic area and further down in your shins and feet work in tandem to absorb shocks to your body from walking, running and other bipedal functions. When you are carrying too much body-fat on your bone structure, you are making things unnecessarily difficult for your knees. (6)
The wearing down of the cartilage in the knees
The bones in your knees are covered in cartilage, which is supposed to provide a smooth, liquid surface for your thighbones, shinbones and kneecaps as they move around as you walk. If you are in the unfortunate position of having a high BMI number and are approaching the obesity scale of the spectrum, then you are more likely to put more force on your knees and as a consequence wear down your cartilage. (7) The cartilage has a limited ability for self-repair using natural body-metabolism processes. (8) This self-repair can take many years to fix problems and may require not only extensive physiotherapy, but in some extreme cases even tissue engineering. (9) The best remedy in this case is prevention, and that is one of the main reasons why knee injuries that have come about through obesity can be avoided entirely by staying fit.
Weight loss and fitness programs recommended
Experts recommend consultation with qualified health-specialists and fitness trainers if you are embarking on a route to reduce body-fat; if you do too much, you risk injuring your muscles and cartilage and worse, sometimes even bones. On the other hand, if you do regular work-outs with proper warm-up sessions under the supervision of a qualified trainer or doctor, then you are less likely to injure yourself as you will understand what your body needs for it to get back on track.
Hormones that increase pain in the knees produced by obesity-process
Another factor that has been shown scientifically to have an effect on the pain you may experience in your knees when you are walking or running if you are overweight or obese is that as body-fat accumulates on your bone and muscle structure, it also gathers into itself various hormones called leptin, adipokines and even cytokines. These substances, which naturally accumulate and layer themselves in between the body-fat cells as they build up, have been shown in clinical tests to have the ability to stimulate pain in your body. (10) Leptin in particular, has been shown to increase pain sensitivity on studies conducted on various test animals.
The causes of knee pain related to obesity then is two-fold: first and foremost there is an accumulation of body-fat that puts unnecessary strain on your joints, particularly the cartilage in the knees; and secondly, if there is body-fat layered around your knees then this has the ability to increase the pain you feel in those areas when you suffer an injury or have to deal with a muscular inflammation due to excessive wear and tear on the knee area. The accumulation of body-fat being too heavy for your genetic bone structure has also been shown to relate to gravity: in the sense that the more weight you are carrying, the more you will feel your mobility being impaired by gravitational forces bearing down on your body.
Major studies clearly show link between obesity and knee pain
A further link between obesity and knee pain was established in clinical trials performed on aging people who were suffering from knee pain. (11) Doctors in this British study tracked changes in people who fell into this category and noticed that those with a BMI higher than 27 (very much into the obese spectrum), made them three times more likely to have recurring knee problems. In addition to this, obesity also raised the risk for already existing pain in the knees to worsen in the patients over that three-year period. In a similar study from the Netherlands, (12) researchers x-rayed patient’s knees over a series of six years and found that the ones in the obese spectrum end of the BMI scale were three times more likely to develop a debilitating condition known as osteoarthritis in their knees.
Whether or not you think these studies are valid or not, or whether you think they were conducted on the correct population groups, the fact remains that if you see a doctor with complaints about knee problems and you are in the obese spectrum of the body mass index scale, your doctor will undoubtedly tell you that the first thing you should do is go on some sort of a weight-loss program and introduce regular exercise to your routine. Doing this will help your medical practitioner in isolating conditions that may be causing your knee pain. With some luck, losing weight and getting regular exercise will make the pain go away and if not, then at least you can remove that as a factor and potentially isolate some kind of a far-more-worrying condition that needs to be caught early on in its development in order to prevent it from becoming a potentially devastating problem, such as arthritis, osteoporosis or osteoarthritis.
---
1. The impact of body build on the relationship between body mass index and percent body fat, Duerenberg, P., Yam M. D., Wang J., Lin F. P., Schmidt G., International journal of obesity, vol 23, no5, pp. 537-542, Basingstoke, 1999
2. ibid.
3. Ideal body weight estimated from the body mass index with the lowest morbidity, Tokunaga K, Matsuzawa Y, Kotani K, Keno Y, Kobatake T, Fujioka S, Tarui S., International journal of obesity, 1991, Jan; 15(1):1-5
4. Reciprocal Relations of Subcutaneous and Visceral Fat to Bone Structure and Strength, Vicente Gilsanz, James Chalfant, Ashley O. Mo, David C. Lee, Frederick J. Dorey and Steven D. Mittelman, The Journal of Clinical Endocrinology & MetabolismSeptember 1, 2009 vol. 94 no. 93387-3393
5. The Association Between Obesity and the Prevalence of Low Back Pain in Young Adults: The Cardiovascular Risk in Young Finns Study, Rahman Shiri, Svetlana Solovieva, Kirsti Husgafvel-Pursiainen, Simo Taimela, Liisa A. Saarikoski, Risto Huupponen, Jorma Viikari, Olli T. Raitakari, Eira Viikari-Juntura, American Journal of Epidemiology. 2008;167(9):1110-1119. 2008, Oxford University Press
6. ibid.
7. The Association of Knee Injury and Obesity with Unilateral and Bilateral Osteoarthritis of the Knee, Maradee A. Davis, Walter H. Ettinger, John M. Neuhaus, Sangsook A. Cho, Walter W. Hauck, American Journal of Epidemiology, Volume 130, Issue 2, pp. 278-288
8. Cartilage Regeneration Using Principles of Tissue Engineering, Solchaga, Luis A. PhD*; Goldberg, Victor M. MD**; Caplan, Arnold I. PhD, Clinical Orthopaedics & Related Research: October 2001 - Volume 391 - Issue - pp S161-S170
9. ibid.
10. Shiri, et. al., 16-18,20,21
11. Obesity and Knee Pain, Eric Metcalf, MPH, Medically reviewed by Pat F. Bass III, MD, MPH, accessed 21st, June 2011, http://www.everydayhealth.com/knee-pain/obesity-and-knee-pain.aspx
12. ibid.