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Barefoot Running

Harvard evolutionary biologist Dan Lieberman believes that modern running shoes may explain why fifty percent of serious runners are injured at least once a year (Nature, January 2010). Modern running shoes have features that cause runners to land on their heels with forces of at least three times body weight at 6-minute mile pace. The faster a runner runs, the greater the force, which causes stress fractures of the feet and lower legs, shin splints, tears in the fascia on the bottom of the feet, knee and hip pain, tendon and joint damage and more.

Hitting the ground with the heel first generates tremendous force because it stops the foot suddenly. On the other hand, landing on the front of the foot allows the foot to keep on moving as the heel is lowered toward the ground to distribute the forces throughout the entire lower leg. If you drop a pen on its tip, it hits with tremendous force because it stops when it hits the ground and then falls forward. However, if the pen were dropped on the side of one end, it would hit the ground with much less force because after hitting on that side, the force would be distributed as the pen falls backward to the other end.

In the 1960s doctors thought that most running injuries were caused by excessive pronation, a rolling inward of the foot after the heal strikes the ground. They felt that the foot rolled inward toward the arch to dissipate the tremendous heel strike forces. This, in turn, caused the lower leg to twist inward and they blamed the frequent running injuries on the inward twisting motion of the leg after heel strike. So they invented running shoes with special arch supports to limit inward rolling, and with padded heels to cushion some of the shock of the heel hitting the ground. However, these features reinforce the runners' habit of landing on their heels.

Dr. Lieberman has shown that barefoot runners are more likely to land on their forefoot or mid-foot. He has shown in elegant experiments that landing on the front part of the foot reduces the force of the foot strike very significantly. However, he has no data to show that running injuries can be prevented by running barefoot. Furthermore, stones and cut glass can cause injuries, and most runners have such thin skin on the bottom of their feet that they couldn't possibly run barefoot.

New on the market are running shoes with very thin soles and minimal heels called Vibram FiveFingers shoe and the Dunlop Volley. Vibram is supporting Dr. Lieberman's studies. Dr. Lieberman has shown only that:
• modern running shoes tend to encourage a runner to land on his heels, and
• heel strike generates more force than front foot strike.
He has not yet shown that:
• modern running shoes cause injuries, or that
• injuries can be treated or prevented by running barefoot or in thin-soled shoes.

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Dear Dr. Mirkin: Can diet help to prevent senility and Alzheimer's disease?

Probably. A study from Columbia University in New York shows that those least likely to develop Alzheimer's disease eat a diet rich in omega-3 fatty acids, omega-6 fatty acids, vitamin E, vitamin B12 and folate, in foods such as nuts, fish, tomatoes, olive oil, poultry, broccoli and other cruciferous vegetables, fruits, and dark green leafy vegetables. They eat less red meat, organ meats and high-fat dairy products (Archives of Neurology, April 2010).

Alzheimer's disease is associated with an overactive immunity called inflammation. Your immunity is good for you because it prevents germs from invading your body. However if your immunity is overactive, it uses the same chemicals that it uses to destroy invading bacteria to punch holes in your arteries and damage your brain (Nature Medicine, August 2009). The foods recommended in the Columbia study reduce inflammation, while red meat and high fat dairy products may increase inflammation. Being overweight also increases risk for Alzheimer's disease because full fat cells release hormones that cause inflammation (Biochimica et Biophysica Acta, May 2009).

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Dear Dr. Mirkin: What can I do about very high triglycerides and low HDL cholesterol?

These blood test results mean that you have metabolic syndrome, a form of pre-diabetes or diabetes that puts you at high risk for heart attacks (JAMA, April 15, 2010). When you eat foods with added sugars, those made from flour, and sugar in liquid form (including fruit juice), your blood sugar rises to high levels. This causes your pancreas to release large amounts of insulin that converts sugar to triglycerides (high triglycerides). Then you use up your good HDL cholesterol in carrying triglycerides from your bloodstream into your liver (low HDL cholesterol).

You should avoid the refined carbohydrates that cause the highest rises in blood sugar, except when you exercise. When muscles rest, they cannot remove sugar from the bloodstream without insulin. However when muscles contract, they draw sugar rapidly from the bloodstream without needing insulin. This effect lasts while you exercise and for up to an hour afterwards, and then tapers off to zero in the next 17 hours. That's why you must exercise every day to reap this major benefit of exercise.

You can avoid diabetes by exercising daily, losing body fat, gaining muscle, eating lots of vegetables, and making sure that your blood level of vitamin D is normal. Lack of vitamin D increases risk for diabetes by blocking insulin receptors and preventing your body from responding to insulin. If your vitamin D3 level is below 75 nmol/L, you are deficient and need more sunlight or vitamin D pills.

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Recipe of the Week:

Artichoke-Wild Rice Salad

You'll find lots of recipes and helpful tips in The Good Food Book - it's FREE

June 21st, 2013
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About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities. Read More
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