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How Endurance Exercise in Later Life May Prolong Lives

Competitive long distance skiers, ages 66 to 77, have longer muscle telomeres and maximal ability to take in and use oxygen (VO2max) than other active people of the same age (PLoS One, online December 26, 2012). Telomere length is a marker of aging. The older you are, the shorter your telomeres. If your telomeres are longer than those of your age group, you are younger than your chronological age and therefore can expect to live longer.

Many studies show that endurance exercise is associated with:

  • greater ability to take in and use oxygen,
  • living longer,
  • less cancer,
  • less diabetes, and
  • fewer heart attacks and strokes.

The authors state: "Our results suggest that endurance exercise training may . . . result in slowing of aging process by maintaining telomere length. The positive association of VO2max and telomere length underscores the importance of aerobic fitness for healthy aging."

HOW TELOMERES PROTECT GENES: Genes govern your health, physical characteristics, susceptibility to disease and how long you live. They are located in chromosomes inside the cells in your body. At the ends of chromosomes are small caps, called telomeres, that protect chromosomes like the plastic tips on shoelaces. They keep the ends of chromosomes from sticking together and losing their ability to tell your cells what to do.

Each time a cell divides, parts of the telomeres break off. Eventually the telomeres become so short that they cannot protect chromosomes from sticking together. This causes aging, certain diseases such as cancers, and eventually death.

HOW EXERCISE PROTECTS TELOMERES: The more intensely you exercise, the more oxygen you need to help convert food to fuel your muscles. When you exercise so intensely that you have to breathe hard and fast, you increase your need for oxygen. It is this markedly increased need for oxygen brought on by intense exercise that helps to slow down the rate that telomeres shorten with aging (Scand J Med Sci Sports, 2010;20: 39-48).

SIGNIFICANCE OF THIS STUDY: In this study and several others, the level of fitness was associated with the length of telomeres. Fitness is measured by VO2max, the maximal ability of your muscles to take in and use oxygen. The higher the VO2max, the greater the length of telomeres in the older competitive athletes.


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One Reason Why Obesity and Diabetes Have Become an Epidemic

The January 2, 2013 issue of the Journal of the American Medical Association has an article with an answer for the obesity and diabetes epidemic that has increased in North America over the last thirty years, even while heart attack rates and deaths from heart attacks have decreased. Dietary sugars, particularly sugared drinks, appear to be responsible for this frightening and life shortening epidemic.

Dietary sugar contains mostly two sugars, glucose and fructose, either bound together as the double sugar sucrose, or separately as individual glucose and fructose. The article shows that glucose makes you feel full so you stop eating, but FRUCTOSE DOES NOT MAKE YOU FEEL FULL SO YOU KEEP ON EATING to become fatter and fatter.

THE STUDY: The authors used brain magnetic resonance imaging to show that eating or drinking glucose, but not fructose, reduced blood flow and activity to the hypothalamus (insula, and striatum), the parts of the brain that tell you when you are full. That means that glucose makes you feel full so you stop eating. Fructose does not suppress appetite, so no matter how much fructose you eat or drink, you can still be hungry.

MECHANISM: Eating glucose causes your pancreas to release large amounts of insulin that suppresses hunger. On the other hand, fructose does not cause your pancreas to release insulin, so you lose the appetite suppressing effect of that hormone.

Before any sugar can be absorbed into your bloodstream, it must first be reduced to a single sugar. Your body never allows double sugars to be absorbed into your bloodstream. Table sugar is a double sugar called sucrose that is made up of single molecules of glucose and fructose bound together, so when you eat table sugar, you get equal amounts of glucose and fructose.

Most sugared, soft drinks contain high fructose corn syrup, a mixture of slightly more than fifty percent fructose and slightly less than fifty percent glucose. This small difference in concentration of glucose and fructose is probably irrelevant. The reason that soft drinks are so fastening is that they are in liquid form.

SUGARED DRINKS ARE MOST FATTENING AND SUGARED FOODS ARE LESS FATTENING, while whole fruits (with their natural sugar) are not very fattening at all. When food enters your stomach, the pyloric valve at the end of your stomach closes and allows only a liquid soup to pass into your intestines. Sugared drinks enter your intestines almost immediately and are absorbed very rapidly, causing a high rise in blood sugar.

Sugared foods must be broken down before they can pass into your intestines to be absorbed. A sugary cookie, made with flour, has tiny particles that are broken down relatively rapidly to cause a high rise in blood sugar, but the rise is not as steep as that from sugared drinks.

Fruits are full of fiber, so the particle sizes are larger and take longer to slip through the pyloric sphincter. Thus orange juice passes immediately into your intestines, while an orange can sit in your stomach for more than five hours. That is why sugared drinks are more fattening than cookies, and fruit is far less fattening because of its delayed passage into your intestines.

HOW SUGAR-ADDED DRINKS AND FOODS LEAD TO DIABETES: Anything that makes you fatter increases your risk for becoming diabetic. Before insulin can do its job of driving sugar into cells, it must first attach to insulin receptors, special hooks on the outer walls of cells. Fat inside a cell prevents insulin from attaching to its receptors and doing its job of driving sugar into cells, so blood sugar levels rise higher and higher as you become fatter and fatter.

HOW HIGH BLOOD SUGAR DAMAGES YOUR BODY: A high rise in blood sugar causes sugar to stick permanently to the outer membranes of cells. This destroys the cells to cause every known side effect of diabetes: blindness, deafness, heart attacks, strokes, dementia, impotence, infertility, nerve damage, lack of feeling, diffuse body pain, and so forth.

WHEN IS IT SAFE TO TAKE SUGAR? I recommend that you take sugared foods or drinks only when you are exercising or shortly after you finish. Resting muscles draw no sugar from the bloodstream to help prevent a high rise in blood sugar. On the other hand, contracting muscles draw sugar rapidly from the bloodstream to prevent a high rise in blood sugar. The more vigorously you contract your muscles, the greater the effect of muscles drawing sugar from your bloodstream. Contracting muscles can draw sugar from your bloodstream without even needing insulin. Seventeen hours after you finish exercising, muscles lose their ability completely to take any sugar from the bloodstream without insulin.


This week's medical history:
Zachary Taylor's Salmonella

For a complete list of my medical history biographies go to Histories and Mysteries


Recipe of the Week:

Paella (Spanish Seafood Stew)

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

January 6th, 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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