Sunday, July 30, 2006

Why is belly fat so dangerous?

If you store more fat in your belly than in your hips, your cells are likely to be resistant to insulin which puts you at high risk for high blood pressure, diabetes, heart attacks, strokes and premature death. In one recent study, researchers measured insulin resistance and compared it to several risk factors for diabetes in men and women: 1) heart-lung fitness; 2) whole-body fatness and 3) abdominal obesity (Diabetes Care, March 2006). They showed that lack of physical fitness and overweight are very significant predictors of diabetes in men and women and that the single most important measure of insulin resistance is storing fat in the belly rather than the hips.

Storing fat in your belly causes you to store excess fat in your liver, which interferes with its function of removing insulin from your bloodstream after it has done its job of driving sugar into cells. When your blood sugar rises after meals, your pancreas is supposed to release enough insulin to keep it from rising too high. If your cells cannot respond to insulin adequately, you are called insulin resistant, your blood sugar rises too high and your pancreas releases huge amounts of insulin. When your blood sugar rises too high, sugar sticks to cells. Once there, the sugar cannot get off the cells and is eventually converted to a poison called sorbitol that destroys the cells to damage nerves, arteries and other tissues throughout your body. Excess insulin acts on your brain to make you eat more and on your arteries to cause heart attacks. More

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Thursday, July 27, 2006

How does altitude affect training?

Athletes in endurance events practice a training technique called "living high, training low". Many years ago, scientists noticed that people who live in the mountains, where the air contains lower levels of oxygen, have higher than normal blood oxygen levels. A limiting factor in events that require endurance is the time it takes to move oxygen from the lungs into the muscles. Since more than 98 percent of the oxygen in the blood is bound to red blood cells, people with high numbers of red blood cells should have higher levels of oxygen and therefore have more oxygen available for their muscles, giving them greater endurance. It appears that living and training at high altitude would improve performance even more, so theoretically, all long distance runners, cross country skiers, bicycle racers and other athletes in endurance sports would benefit from living and training at high altitudes.

However, you can’t train as intensely in the mountains where oxygen is sparse. Lack of oxygen during hard exercise slows you down. One group of researchers decided to see if living at high altitudes would increase red blood cell concentration, and training at low altitude would allow the athletes to take harder workouts. Eleven trained middle-distance runners were tested before an 18-day training session in which they slept in special low-oxygen pressure chambers and trained at sea level with oxygen-rich air (Journal of Applied Physiology, January 2006). The tests were repeated 15 days after the training. The athletes who lived high and trained low had higher maximal oxygen uptakes, higher maximal aerobic power and lower resting heart rates than the control group. The blood of these athletes could carry more oxygen, and the oxygen concentration in their bloodstream would return to normal earlier after intense competitions so their performance would improve.

Barometric pressure chambers are avaiable for about $5000, so serious endurance athletes can "sleep high" and train wherever they live.

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Monday, July 24, 2006

Will hard exercise damage my heart?

In 1924, famous cardiologist Paul Dudley White claimed that "exercise can’t hurt a healthy heart". Over the years, several poorly-controlled studies have shown that ultra-endurance events, such a running a marathon, might impair heart function. Now a study from Northwestern University shows that Dr. White is still correct (Journal of the American Society of Echocardiography, February 2006). The authors tested 45 patients before they ran the Chicago Marathon and re-tested them one month after the race. They demonstrated that the race had not caused any abnormalities in heart function.

This does not mean that everyone can go out and run a marathon. People who have damaged hearts can die from over- exertion. If you are a middle-aged person who is thinking about starting a vigorous exercise program, you should get a stress test, an electrocardiogram done while you are exercising vigorously. Tests done while a person is at rest often do not pick up blockages in the arteries leading to the heart. If your stress test shows warning signs, you may need further tests. If you pass your stress test, the odds are strong that you can start your exercise program safely. Once you have your doctor's approval, begin your exercise program gradually to build up the strength of your skeletal muscles and your heart over several months. Then you will be ready to start serious training for your marathon or other endurance event.

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Sunday, July 23, 2006

How does exercise lower blood pressure?

If humans are like rats, those with high blood pressure will live longer when they exercise, even if their blood pressures do not return to normal. Rats can be bred to develop a genetic trait in which they develop high blood pressure, but when they exercise, they live much longer than the rats that do not exercise (Medicine & Science in Sports & Exercise, May 2006).

Having high blood pressure can kill you. It increases your chances of suffering a heart attack, stroke, or kidney disease. Exercise usually lowers high blood pressure because high blood pressure usually is determined by blood volume. Anything that reduces blood volume also reduces high blood pressure. That’s why diuretics are the most effective drugs to lower high blood pressure. Exercising for a few minutes usually does not lower high blood pressure, but exercising for several hours dehydrates you and usually does lower high blood pressure. This study shows that even if exercise does not lower high blood pressure in rats, it still helps them to live longer, and the same may apply to you. More

Friday, July 21, 2006

Dehydration: prevent with sports drinks instead of water?

Sports drinks are no better than water for preventing dehydration. Sports drinks contain a small amount of salt, but not enough to meet your needs. A study in the British Journal of Sports Medicine showed that you cannot replace salt lost through exercise exclusively by taking salty fluids (April 2006). If you are exercising for a long time in warm weather, you need to replace fluid, salt and calories. Salty drinks taste awful, so none of the popular sports drinks contain much salt. You need to eat salty foods along with the beverage of your choice. Since thirst is a very late sign of dehydration and lack of fluids during endurance exercise can kill, all exercisers are encouraged never to wait for thirst to tell them when to drink. By the time an athlete becomes thirsty during a competition, it is too late to drink enough to replenish the fluid loss without stopping to rest.

Many people fear hyponatremia (collapse or even death from too much water during exercise), but sports drinks offer no advantage over any other beverage. Hyponatremia is caused by excess fluid from any source, not by lack of salt or calories. During intense competition, athletes concentrate so hard on maintaining their pace that they are unlikely to take in too much fluid. However, novice athletes often run so slowly that they spend more time drinking than pushing the pace. How much fluid should you drink? The American College of Sports Medicine recommends about a quart an hour during vigorous exercise. For a person who is not exercising near his maximum, this could be too much. The person who is exhausted and exercising significantly below his capacity probably should take in only about a pint per hour. More on hyponatremia

Thursday, July 20, 2006

Can cholesterol be controlled with exercise?

Studies over the last 60 years have shown that people who exercise are healthier than those who do not. Over the last 10 years, many studies have shown that the more intense the exercise, the greater the protection. A report from Italy shows that physical activity is very important in helping to control cholesterol (Clinical Chemistry and Laboratory Medicine, Volume 44, 2006). Healthy male sedentary controls had their blood cholesterol fractions compared to those of male professional cross-country skiers and professional road cyclists.

The athletes had much more healthful numbers for total cholesterol, the good high-density cholesterol, triglycerides, and the bad low-density lipoprotein cholesterol. The concentration of another heart attack risk factor called Lp(a) or lipoprotein(a) was the same in both groups because it is a hereditary factor that is not influenced by lifestyle. Every single scale of susceptibility for heart attacks except the Lp(a) was better in the athletes. More

Wednesday, July 19, 2006

Will nonsteroidals help me recover from a hard workout?

Lots of athletes and exercisers take ibuprofen, an over- the-counter medication, and other nonsteroidals to ease pain in their joints and muscles. A study from the University of Florida (Medicine and Science in Sports and Exercise, May 2006) shows that nonsteroidal drugs inhibit exercise-induced muscle growth and strength.

Athletes train by taking a hard workout and damaging their muscles. They feel sore on the next day and exercise at reduced intensity until their muscles are healed. When they feel no soreness, they take a hard workout again. When muscles heal from the stress of a hard workout, they are larger and stronger. Damaged muscles release a healing prostaglandin called Cox-2, that causes muscle growth and increased strength. Ibuprofen blocks Cox-2 and therefore will delay or inhibit muscle growth. Pain medicines may make you feel better, but at the cost of interfering with the strength gains you are working to achieve.

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Tuesday, July 18, 2006

Did Lance Armstrong cheat?

This month, some of the favorites to win the Tour de France endurance bicycle race were prevented from entering because of suspicion that they may have taken drugs or had blood transfusions to raise their red blood cell counts. That brings up the accusation that Lance Armstrong, possibly the most dominant endurance bicycle racer of all time, took blood boosting drugs when he won the first of his seven Tour De France victories.

The allegation is that Lance Armstrong’s urine, kept in storage for six years, had a positive test for EPO, a restricted drug that raises blood levels of oxygen-carrying and performance-enhancing hemoglobin. An article published in the prestigious medical journal, Blood (June 15, 2006) shows that after competing in any athletic event, any athlete could have a false positive urine test for EPO.

The test for EPO is done by injecting the protein, EPO, into animals so that their bodies produce special proteins called antibodies that attach to EPO. The antibodies are put on a special plate, and the test urine is added. If the urine contains EPO, a band consisting of the antibody tied to the EPO appears on the special plate.

Researchers at Catholic University of Leuven in Belgium showed that “this widely used test can occasionally lead to the false-positive detection of EPO in postexercise, protein-rich urine.” Any athlete can have a false positive test with this procedure. Most people with healthy kidneys do not spill protein in their urine, but after strenuous exercise, athletes with normal kidneys often spill protein into their urine. For example, more than 80 percent of runners spilled protein into their urines after running the Boston Marathon. The authors state that the antibodies that are used in the test can attach to any protein in the urine, not just EPO.

Monday, July 17, 2006

How to start a running program

If you think you would enjoy jogging or running, here's how to get started. First, check with your doctor and get a good pair of running shoes. Start out by jogging slowly until your legs feel heavy or hurt or you feel tired. Then stop for the day, even if you have taken only a few steps. Do this every day or every other day. You should be able to work up to the point where you can jog slowly for at least 20 minutes. If you're happy with this program, you don't have to go any further. However, if you want to improve, follow the training methods that competitive runners use.

On one day, start out slowly and gradually pick up the pace. When you start to feel uncomfortable, slow down. When you recover, pick the pace up again. On the next day, if your legs feel stiff, don't try to run. If you feel all right, run very slowly. Try to do these gradual pickup workouts every other day. Never do them when your legs are stiff or tired.

After a few months of alternating days of pickups and slow runs, you are ready to take the next step: intervals and longer runs. On Tuesdays and Thursdays, run faster. On Tuesday, try to run 220 yards fast (half a track length), rest and then repeat the 220 yard runs until your legs start to feel stiff. On Thursday, try to run two to five miles fairly fast, and on Sunday, try to increase your distance so you can run for at least one hour. On the other days, either run slowly, or if your legs feel stiff, take the day off.

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Friday, July 14, 2006

Will eating gelatin make my nails less brittle?

In the 1890s, Mrs. Charles Knox made her own gelatin by boiling left-over slaughter-house waste of cow's hooves, bones, tendons and skin. She and her salesman husband devised a method of drying sheets of gelatin and grinding them to a powder. They claimed that gelatin would make fingernails stronger, presumably because cow hooves are strong. You can still buy Knox's gelatin, and some people still believe the old advertising claims, even though there is no evidence that gelatin has any effect on nails.

Gelatin does not contain any special nutrients. It contains protein, but lack of protein is not the cause of brittle and cracked nails. Even if protein deficiency caused brittle nails, gelatin would be a poor choice, because it is very low in two of the protein building blocks, tryptophan and lysine. You can meet your needs for protein by eating any food source of protein, such as beans, meat, fish or chicken.

If you have deformed nails, check with a dermatologist to see if you have a fungus infection that can be treated. If you have nails that just peel, crack and break, you probably have a genetic defect that causes your nails to lose moisture. The most effective treatment is to use nail polish to slow the loss of moisture, and to keep the nails very short.

Thursday, July 13, 2006

Regaining lost weight?

Mark Twain told us that giving up smoking is easy; he did it every day. The same applies to losing weight. At some time in their lives, most North Americans have lost more than ten percent of their weight and many have kept it off for at least one year. However, almost all regain that weight. It is extremely uncommon for a person to lose more than 20 pounds and keep it off for the rest of his or her life.

If you want to lose weight and keep it off, you have to make major, permanent lifestyle changes. Start an exercise program that involves others; you are more likely to do it for the rest of your life if your exercise is a social event. Join a running group or bicycle club, or participate in an exercise class such as aerobic dancing. In addition to a regular exercise program, you need to change your kitchen forever. Avoid stocking foods that raise insulin to high levels, which means avoiding all refined carbohydrates: foods made with flour, white rice or milled corn, and all added sugars. Limit concentrated sources of calories such as meat, dairy products (except skim) and added fats such as oils or butter. Most of your food should be whole grains, beans and other seeds; vegetables and fruits. This is a lifelong way of eating, not a short-term diet.

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Wednesday, July 12, 2006

Cross-training prevents injuries

Triathletes are injured only about one third as often as marathon runners even though they do far more work in their program of swimming, cycling and running. Training intelligently for three sports is less likely to injure you than training very hard for one. Training is limited by damage to skeletal muscles. Every time you exercise, your muscles develop small tears with bleeding. It takes at least 48 hours for muscles to heal from exercise. Each sport stresses a particular group of muscles most. Marathon runners who train every day stress the same muscles and do not allow adequate time to recover from the previous day's workout, so they are at increased risk for injury.

Top triathletes train in different sports on consecutive days. Running stresses the lower leg muscles most, cycling stresses the upper leg muscles most and swimming stresses the arms and shoulders most. Triathletes usually set up a workout schedule that includes two sports on one day and one on the next. Of the three sports, running causes the most muscle damage. Muscles are protected by the water in swimming and by the rotary pedal motion in cycling. However, the force of the footstrike in running tears up muscles. So a knowledgeable triathlete runs on one day and cycles and swims on the next. This way each stressed muscle group has a 48-hour recovery before the next workout. You can apply these same rules for alternating any two or three different activities.

Tuesday, July 11, 2006

Does eating before exercise cause cramps?

If you are going to exercise vigorously for more than an hour, you need to eat before you exercise or your muscles and liver will run out of sugar and you will tire earlier. Your brain gets more than 98 percent of its energy from sugar in your bloodstream. But there is only enough sugar in your bloodstream to last three minutes. So you liver has to constantly release sugar from its cells into your bloodstream. There is only enough sugar in your liver to last about an hour when you exercise vigorously. Eating before exercising can help you to exercise longer. If you do not eat before you exercise for more than an hour, and during exercise that lasts more than two hours, your liver will probably run out of sugar. Your blood sugar level can drop, and you will feel terrible fatigue and tiredness.

Whenever your stomach fills with food, its muscles contract and require large amounts of blood. When you exercise vigorously, your heart pumps large amounts of blood to your skeletal muscles. If your heart is not strong enough to pump blood to both your stomach and your skeletal muscles, blood is shunted from your stomach muscles, the muscles lack oxygen, lactic acid builds up in muscles and they start to hurt. However, most people can exercise after eating without suffering stomach cramps because their hearts are strong enough to pump blood to both their exercising muscles and their stomach muscles.

Another theoretical concern is that eating sugar before you exercise will cause your blood sugar level to rise and your pancreas to release insulin, which will cause your blood sugar to drop too low so you will feel tired. However, the major cause of tiredness that you feel in your muscles during exercise is lack of stored sugar in muscles. Taking any extra calories before and during exercise helps to preserve the sugar that is stored in muscles and help you to exercise longer. If you are going to exercise for more than an hour, eat or drink anything you like before and during your exercise. Most people will not get stomach cramps while exercising, no matter what or when they eat.

Monday, July 10, 2006

Carry weights while jogging? Pros and cons

The only advantage to exercising while carrying weights is that you can get more exercise while moving slowly. To strengthen your heart, you have to exercise vigorously enough to increase your heart rate at least 20 beats a minute above resting. How fast your heart beats depends on how much blood it has to pump to your body. When you run and carry hand weights, your heart has to pump blood to your exercising leg muscles and also has to do extra work to pump blood to your arm muscles. That means that you can achieve the same heart rate when you run more slowly.

Competitive runners should never carry hand weights. How fast you run in races depends on how fast you run in practice. Carrying hand weights slows you down, so you become a slower runner. Carrying weights also interferes with the natural motion of your arms while running. On the other hand, carrying weights can help to protect people who develop frequent running injuries. Carrying hand weights slows them down, so less force is directed at their leg muscles while they run. Hand weights will not do much to increase your arm strength, because to become stronger, you have to lift progressively heavier weights.

Sunday, July 09, 2006

Do former athletes live longer?

Studies have shown that Harvard and University of Michigan varsity letter-winners do not live longer than their less-athletic classmates, but people who exercise regularly as they age live three to seven years longer than non-exercisers. Other studies show that athletes are no lower risk of heart attacks later in life than their less athletic peers UNLESS they continue to exercise as they age. Former athletes who continue to exercise have lower blood levels of the bad LDL cholesterol, total cholesterol, triglycerides and higher levels of the good HDL cholesterol that prevents heart attacks.

It's called reversibility. Every benefit gained by exercising is lost soon after you stop. Muscles enlarged by lifting heavy weights return to their previous size within a few weeks after you stop lifting. People who do aerobic exercise lose their slow heart rates and greater endurance soon after they stop regular workouts.

Regular exercise is the most effective way to prevent the gradual weight gain that often comes with aging. If you're tired of being out of shape, check with your doctor. Then pick a continuous sport that you will enjoy doing, such as walking, swimming, cycling or dancing. Start out by exercising slowly and comfortably until your muscles start to feel heavy or hurt, and then stop for the day. Do this every other day and gradually increase the time you spend exercising, always stopping when your muscles feel heavy or hurt. When you can exercise continuously for 30 minutes, three times a week regularly, you are fit and don't need to do more unless you want to.

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Thursday, July 06, 2006

Heart tired during exercise?

A healthy heart is so strong that it is almost never a cause of tiredness during exercise. Tiredness during exercise comes from your muscles. They run out of fuel or out of oxygen. Skeletal muscles use both fat and sugar for energy. When your muscles run out of their stored sugar supply, called glycogen, they cannot contract and function adequately. You feel tired, your muscles hurt and you have difficulty coordinating them. On the other hand, your heart muscle gets energy directly from fat and sugar in your blood and even from a breakdown product of metabolism called lactic acid. It is virtually impossible for the heart muscle to run out of fuel unless you are starving to death.

A healthy heart doesn't run out of oxygen either. Oxygen comes to the heart directly through arteries on its outside surface. If these arteries are not plugged up with plaques, they are large enough to supply all the oxygen that the heart can possibly need. However, fatty plaques in arteries can block the flow of blood. When the heart does not get enough blood, it will hurt and can start to beat irregularly. Exercise won't make a healthy heart hurt. If you develop heart pain during exercise, something is wrong and you need to check with a doctor immediately.

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