Maximum heart rate gets lower as you get more fit

A study from Liverpool, England shows that the maximum heart rate for athletes is lower than for aged-matched sedentary people. At first glance, this makes no sense because you would think that the faster you heart can beat, the more blood your heart could pump and the better an athlete you would be. However, a stronger heart pumps more blood with each beat, so stronger hearts don't have to beat as often. This means that as you become more fit, your maximum heart rate will get lower, not higher.

Virtually everyone agrees that heart rate depends on the amount of blood pumped toward it by exercising muscles. When you contract your leg muscles during exercise, muscles squeeze veins near them to pump blood toward the heart. Then when leg muscles relax, the veins fill up with blood. The pumping action of leg muscles during exercise forces extra blood to the heart, which causes the heat to beat faster and contract stronger. This is known as the Bainbridge reflex. We know this is true because we are able to transplant hearts. If nerves inside the heart regulated heart rate, the heart would not be able to control its rate of beating since the nerves are cut during the transplant.

Since the strength of leg muscles determines the fastest that your heart can beat and still pump blood, you might expect that athletes with stronger muscles would have faster heart rates. However, they don't. The researchers at John Moores University in Liverpool showed that athletes have lower maximum heart rates than sedentary people (International Journal of Sports Medicine, January 2008). The maximum heart rate of male athletes was calculated to be 202 - 0.55 × age, and for female athletes, 216 - 1.09 × age. Both weight lifters and runners had similar maximum heart rates, which were significantly lower than the age-matched sedentary people. The athletes have hearts that can pump more blood with each beat than the hearts of sedentary people, so they do not beat as often.

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How to Recover from an Injury or Surgery

Is it better to rest completely or exercise gently while recovering from an injury? According to a study from the University of Wisconsin in Madison, it is better to exercise at low intensity while recovering from an injury or surgery. The researchers found that motion during recovery limits muscle atrophy, accelerates tendon healing, and prevents joint stiffness. This explains why most doctors refer their injured or post-surgical patients for physical therapy and rehabilitation exercises.

If you are in reasonable shape and stop exercising for any reason, your muscles become smaller and weaker and are at increased risk for injury when you return to exercising. Gentle stress on a muscle or tendon can help to prevent this loss of strength. Mild exercise is a stimulus for cell growth. However, if you pull too hard on a weakened muscle or tendon, you can tear it and delay recovery.
Journal reference

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Cold Air Won't Freeze Your Lungs During Exercise

It's almost impossible to damage your lungs by breathing cold air when you exercise. More than 70 percent of the energy produced by your muscles during exercise is lost as heat. This extra heat can be used in your nose and bronchial tubes to warm the air as it travels to your lungs. Air inhaled at 40 degrees below zero Fahrenheit will be warmed to more than 100 degrees by the time it reaches your lungs, so your lungs will not suffer from frostbite.

However, air that cold will burn your nasal membranes and cause pain in your nose that is so severe that you will lose interest in exercising very quickly and look for shelter. To protect your nose in very cold weather, you can cover it with a scarf, balaclava or face mask placed over your nose and mouth.
More on frostbite

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Longer Telomeres Mean Longer Life

If you need proof that exercise helps to keep you young, look at the exciting study from King's College in London, England reported in the Archives of Internal Medicine (January 28, 2008). The researchers showed that people who exercise regularly have telomeres in the DNA of their white blood cells that are longer than those of couch potatoes. White blood cell telomeres shorten over time and serve as a marker of a person's biological age.

The active ends of genetic material in cells are covered with a layer of proteins called telomeres. If they weren't, the exposed ends of the genetic material would stick to anything nearby and the cells would die. However, each time a cell divides to make two cells, a little bit of the telomere is removed. Eventually the telomere is gone, the ends of genetic material stick together and the cell can no longer divide so it dies without replacing itself. Obviously, the longer the telomeres, the longer it will take for the telomeres to be used up so the cells are viable longer.

The study compared physical activity, smoking and socioeconomic status in 2,401 sets of twins. Those who were more active had longer leukocyte telomeres than those who were less active. The researchers concluded that "The mean difference in leukocyte telomere length between the most active (who performed an average of 199 minutes of physical activity per week) and the least active (16 minutes of physical activity per week) subjects was 200 nucleotides, which means that the most active subjects had telomeres the same length as sedentary individuals 10 years younger, on average."
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Dry Skin Means Lack of Water, Not Lack of Oil

Dry skin means lack of water, not lack of oil. Skin creams function by creating a temporary barrier on your skin that seals in water.

In the late 1940's, a doctor at Massachusetts General Hospital took a hard callus off the foot of one of his patients and placed in oil. It remained as hard as ever. Then he placed the callus in water and it became very soft, but soon after being removed from the water, it became very hard again. Then he left the callus in water until it became soft, removed it and then soaked it in oil and it remained soft for a long time. He had shown that dry skin should be treated by using oils and creams to seal in moisture. Cosmetic manufacturers soon produced oil-in-water emulsions which were incorporated into creams designed to seal in water.

However, some studies show that oil-in-water emulsions soak off the outer layer of skin and increase its susceptibility to irritation from cold, rubbing, and various chemicals that you may be exposed to, such as ingredients in cleaning products or cosmetics. The longer skin is immersed in water, the more protective outer coatings of skin is stripped off. Take quick showers and decide for yourself whether using a cream or lotion helps you or not.

All lotions and creams work the same way, no matter how much they cost or what special ingredients they claim to contain. Just pick one that feels and smells pleasant to you.

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How exercise prevents diabetes: more than just weight control

A fascinating study from Maastricht University in the Netherlands shows that exercise helps to prevent and treat diabetes by increasing the number of enzymes that transport fat from fat cells to muscle cells where it can be used for energy by the muscles. Before insulin can do its job of removing sugar from the bloodstream and putting it into cells where it can be burned for energy, it must first attach on special hooks called insulin receptors on the surface of cells. Fat stored in cells internalizes receptors so insulin loses its attachment sites and is unable to its job. Exercise causes muscle cells to markedly increase their production of certain fat transported proteins that remove fat from fat and muscle cells. So less fat is available to block insulin receptors and blood sugar levels drop. Journal reference

Another study, from University of California at Berkeley, followed 36,000 male runners for almost a decade. Those who ran five or more miles per week were half as likely to develop diabetes as those who ran fewer than five miles per week (Diabetes Care, November 2007). Furthermore, researchers at the University of Western Australia showed that an eight-week exercise program markedly increased diabetics' ability to respond to insulin, even if they did not lose any fat. Journal reference

Anyone who wants to prevent diabetes should make exercise a priority. Because of the extremely high rate of heart disease in diabetics, all diabetics should have their hearts checked by a cardiologist. If they can pass a thalium stress test, they should be in some kind of supervised exercise program. More

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Knee Cartilage Repair: Will it Work for You?

The ends of bones are soft, so they must be covered with a thick white gristle called cartilage. Once damaged, cartilage can never heal. When knee cartilage is damaged, the person spends the rest of his life losing more cartilage until it is completely gone and the knee hurts 24 hours a day.

If only a small area of the cartilage is damaged, it may be repaired with cartilage extracted from your own body. (If cartilage is taken from someone else, your immunity will try to kill it, but it doesn’t try to kill your own cartilage.) Your extracted cartilage is grown in special culture dishes and then injected into a hole in your own cartilage and secured in place. This procedure works very well if you have only a small piece of cartilage missing. The doctors just fill the hole. However, unless they can enclose the entire area for the donor site, the cartilage will not stay where it was put and will not be beneficial. That is why this procedure cannot be used to treat a cracked cartilage in the knee. Remember they have to cover the articular surface that meets the cartilage from the other side of a joint.

When all the cartilage in your knee is gone, the only effective treatment is to replace the whole knee. Knee replacements are now lasting for twelve to twenty years or more, and most remain pain-free.

If you have damaged cartilage in your knee, you should protect that knee for the rest of your life. Running, fast walking and jumping cause further damage, while pedaling and swimming usually do not. When the knee hurts all the time, your doctor will check to see how much cartilage is left. If it's gone, you probably need a knee replacement.

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