If you're putting off getting into a regular exercise routine because you're worried that exercise contributes to arthritis, think again. Studies show that exercise can be safe for joints, both in older, overweight folks and in athletes.
The knees of Framingham
In 1948, more than 5,200 residents of Framingham, Mass., volunteered for the Framingham Heart Study, which has produced major insights into the causes of heart attack and stroke. In 1971, scientists began a new study of the children of the original volunteers and the spouses of those children. Between 1993 and 1994, 1,279 members of the Framingham Offspring Cohort enrolled in a study of exercise and arthritis. Their average age was 53.
All the volunteers were free of arthritis when the study began. Each answered detailed questions about their patterns of exercise, including walking, jogging, being active enough to work up a sweat, and their overall exercise level. All the people provided information about knee injuries and symptoms of knee pain and stiffness. In addition, all the volunteers were weighed and measured, and they each had a full series of knee x-rays.
Between 2002 and 2005, the subjects answered the same questions about knee pain and injury, and the x-rays were repeated. All the x-rays were independently evaluated by two experts who had no knowledge of the subjects' exercise histories.
When the results were tallied, the researchers found no link between exercise and arthritis of the knee. The most active people had the same risk of arthritis as the least active, in terms of both symptoms and x-ray abnormalities.
Exercise was as friendly to the knees of joggers as walkers, even though jogging subjects the lower body to much higher impact and stress than walking. And even though obesity is an independent risk factor for arthritis, physically active overweight members of the study group fared just as well as their slim peers.
Although the Framingham study goes a long way toward dispelling the idea that exercise causes arthritis, it did not confirm a fond hope of exercise enthusiasts: that repetitive exercise could be good for joints.
However, a high-tech Australian investigation of 297 men and woman without knee injuries or disease showed that people who performed the most vigorous weight-bearing exercise had the thickest, healthiest knee cartilage.
A 2008 study that compared 284 dedicated runners with 156 nonrunners also found little evidence that exercise causes arthritis. After a remarkably long 21-year follow-up period, the runners experienced significantly less musculoskeletal disability than did their less active peers — and the runners also enjoyed a 39% lower mortality rate.
The research is impressive, and it confirms earlier studies. Former varsity runners, for example, are no more likely to develop arthritis in their legs than former college swimmers, and champion runners are no more likely to end up with arthritic hips than nonathletes.
Exercise as therapy?
Exercise is often prescribed for patients with arthritis. Exercise may be safe for healthy joints — but is it also safe for arthritic joints?
In 2005, British researchers found that both walking and muscle-strengthening were safe and effective, reducing pain and disability in people with arthritis. And in 2006 and 2007, scientists in the Netherlands and the U.K. reported that graded exercise programs are safe and effective for patients with arthritis of the hip or knee.
Healthy body, healthy joints
To prevent problems caused by exercise, be sure your general health is good; older people and patients with heart disease, high blood pressure, diabetes, or other significant problems should get medical clearance. And all of us should get in shape gradually. Listen to your body as you exercise and report any problems to your doctor.
Warming up and cooling down will help protect your heart and your joints. Stretching exercises, good shoes, and good technique will also reduce your risk of musculoskeletal injuries. With these simple precautions and a dose of common sense, exercise will be safe for your joints.
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Cinnamon as treatment for diabetes?
Q. I've heard that you can treat diabetes by taking an extract from cinnamon. I suspect this is snake oil, but is there anything to it?
A. A few years ago, I heard the same thing from a friend. My first reaction was like yours, but my friend was knowledgeable about food and suffered from type 2 diabetes, so I looked into it. There have been several published scientific studies — randomized, placebo-controlled trials — of cinnamon in patients with type 2 diabetes or prediabetes. Most involved relatively few people (between 20 and 60) and lasted a short time (a few weeks). A slight majority showed that cinnamon reduced blood sugar more than placebo, but the other studies didn't show a benefit.
Whenever some improbable treatment is reported to work, and I'm not sure I believe it, I look for a biochemical explanation. With cinnamon and diabetes, there is one, and it involves glucose, insulin, and insulin receptors.
Glucose is the simple sugar that circulates in the blood. All cells depend on it for energy, so glucose needs a way to get from the bloodstream into cells. Insulin is a hormone that also circulates in the blood. When insulin attaches to structures on the outside of cells called insulin receptors, it's as if doors to the cells swing open and glucose is allowed in. In people with type 2 diabetes, cells resist this effect of insulin, so glucose doesn't get into cells and builds up in the blood instead.
Cinnamon contains several chemicals that stimulate insulin receptors so glucose can get into cells and that means levels in the blood go down. There's some debate about exactly which chemicals are the critical ones.
So cinnamon as a treatment for diabetes may not be pure snake oil. But hang on. I also think studies with many more people for longer periods of time need to be done before we get too excited about this "natural" treatment. My guess is that cinnamon and other foods may have some value in treating type 2 diabetes, but probably as adjuncts to, rather than as substitutes for, conventional medicine.
— Anthony L. Komaroff, M.D.
Editor in Chief, Harvard Health Letter
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