Saturday, January 24, 2009

Exercise Protects against Inflammation

Researchers from Ataturk University in Turkey showed that hard exercise protects you from inflammation by raising blood levels of the antioxidants superoxide dismutase, glutathion peroxidase and glutathione S-transferase (The Journal of Sports Medicine and Physical Fitness, September 2008). During vigorous exercise, food exposed to oxygen is converted to energy by transferring electrons from one chemical to another. If the transferred electron ends up on hydrogen, it is converted to water and is harmless. If it ends up on oxygen, it forms free radicals that can damage your genetic material and cause cell damage. To protect you, your cells produce antioxidants. Exercise protects you from free radicals by causing your cells to produce large amounts of antioxidants.

Tuesday, January 20, 2009

Greater Endurance with Aging

I’m 74 years old and ride my bicycle more than 200 miles per week, often in pace lines with younger riders. I have noticed that younger riders can easily pull away from me in short bursts, but I keep coming back on them and seem to be better able to keep up with their accelerations as the ride progresses.

The latest issue of Exercise and Sports Sciences Reviews (January, 2009) reviews the entire world’s literature to show that endurance improves as you age. Wow!

The maximal muscle contraction force occurs when you do a single muscle contraction with all your might. Even though older people are not as strong as younger ones, many studies show that they can retain maximal force after many contractions far longer than younger people can.

Here’s the theory and evidence to explain why aging improves endurance. Muscles are made up of millions of individual fibers just as a rope is made up of many different threads. Each muscle fiber is enervated by a single nerve. As you age, you lose nerves throughout your body and when you lose the nerve that enervates a specific fiber, you also lose that muscle fiber.

Muscle fibers are classified as type I endurance fibers and type II strength and speed fibers. With aging, you lose far more nerves that enervate the strength and speed fibers than those that enervate the endurance ones. So, with aging, you lose strength but you retain a greater proportion of endurance fibers.

Muscle fatigue comes from the accumulation of waste products that occurs while food is converted to energy to power your muscles. Scientists can measure fatigue by measuring the accumulation of acid (H+), Phosphate (Pi) and protonated phosphate (H2PO4) in muscle. With the same percentage of their maximal muscle force, older people accumulate far lower levels of these end products than younger people do. Therefore even though older people are weaker, they can maintain their forceful contractions far longer than younger people can and they have greater endurance. This exciting recent data will encourage me to train even harder.
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Sunday, January 18, 2009

Cold or Fever: Should You Exercise?

Exercise may actually be beneficial when you have a cold. However, it's probably better to stop exercising altogether if you have a fever with aching muscles. When you exercise, your heart has to pump blood to your muscles to supply them with oxygen. It also must pump blood from your muscles to your skin where the heat is dissipated. When you have a fever, your heart has to work harder to get rid of extra heat.

You risk injury if you exercise when your muscles hurt at rest. When muscles are damaged, they release enzymes from their cells into the bloodstream and they fill with blood from broken blood vessels. One study reported markedly increased muscle damage during relatively minor exercise during an infection, with blood tests showing increases in muscle enzymes and ultrasound tests demonstrating hemorrhage into the muscles. You will not lose much conditioning if you take off a few days.

Thursday, January 15, 2009

How Exercise Preserves Brain Function

Dr. Yu-Min Kuo, of the National Cheng Kung University Medical College in Taiwan, has shown how exercise helps to preserve brain function as you age (The Journal of Applied Physiology, November 2008). Dr Kuo trained mice to run daily for five weeks on wheels at 70 percent of their capacity. They started to exercise at 8, 12 and 24 months of age. These ages are equivalent in humans to ages of 40, 60 and 90 years.

The mice that exercised every day grew 2.5 times more new brain cells than those who did not exercise, and these new nerves helped them to learn and memorize new tasks. The increase in brain cells came from increased production of signaling molecules that promote brain cell growth.

However, the mice that started exercise in early middle age (equivalent to age 40) did much better than mice that did not start exercising until later middle age (equivalent to age 60). This would indicate that the capacity of exercise to help you maintain intelligence decreases after middle age.

When you are young, your body continuously creates new brain cells. As you age, your brain loses its ability to regenerate new nerve cells. This is why you gradually lose some of your ability to remember and learn. We don’t know if Dr. Kuo’s results would be found in humans, but his study should encourage people to start exercising while young and continue throughout their lives.