How Exercise Keeps You Young (and Prolongs Your Life)

Dr. Mark Tarnopolsky, of McMaster University in Hamilton, Ontario, has shown that exercise prevents aging in mice programmed to grow old rapidly (The Proceedings of the National Academy of Sciences, September 22, 2010). The exercising mice did not have the expected shrinkage with aging of their brains, hearts, muscles, skin, hair, ovaries, testicles, spleen, kidneys, and liver. Many other studies show that exercise in later life slows signs of aging such as loss and graying of hair, weaker and smaller muscles, loss of brain function and size, thinning of skin, damage to blood vessels associated with heart attacks and strokes, loss of apoptosis associated with increased cancer risk, and loss of sexuality associated with shrinking of testicles and ovaries.

The explanation for these incredible findings appears to be in the mitochondria that convert food to energy for your body. At all ages, the exercising mice appeared younger and healthier than the non-exercising mice. Mitochondria have a different DNA than other cells in mammals. That means that in the process of evolution, bacteria invaded cells and provided the ability to turn sugar to energy more efficiently than any other process in the body. Aging in humans is associated with loss of function and number of mitochondria which causes decline in tissue functions that causes cancers, arteriosclerosis, diabetes, and Parkinson's and Alzheimer's disease. With aging, genetic mutations cause mitochondria to malfunction and die and you to look older.

As you age, you lose your ability to make AMP-activated protein kinase, also known as AMPK (Cell Metabolism, February 2007). This enzyme functions to increase mitochondria in muscles. Anything that reduces the number or efficiency of mitochondria interferes with your body's ability to burn fat and sugar for energy. As a result, blood sugar, fat and cholesterol levels rise. Most cells in your body contain many mitochondria, small furnaces that burn food for energy. With aging, the number and the efficiency of mitochondria both decrease. This interferes with your body's ability to turn food into energy. The extra calories that are not burned accumulate in your body as fat in your muscles, liver and fat cells. This causes you to gain weight. Extra fat in cells block their ability to take in sugar from the blood stream, so blood sugar levels rise and you are at increased risk for developing diabetes. Extra fat in the liver prevent the liver from removing extra insulin, so insulin levels rise to constrict arteries and cause heart attacks. Insulin also makes you hungry all the time to increase your chances of gaining weight.

AMPK is increased by exercise and by drugs used to treat diabetes, such as metformin or Actos. The best way to increase the number and size of mitochondria in your cells is to exercise. If you do not have a regular exercise program, you are shortening your life. How exercise strengthens mitochondria and prevents aging

The benefits reported in mice appear to apply to humans. For the last two years, Diana and I (ages 69 and 75) have been part of group of tandem bicycle riders, ages 40s to 70s, who race flat out for 25 to 30 miles three times a week and ride more than 100 additional miles in the rest of the week. All look younger, are thinner and more muscular, and are far more active than their same-age contemporaries in The Villages, Florida where we live.