Saturday, December 31, 2005

How does exercise make bones stronger?

Bones are not static. Certain cells called osteoblasts constantly bring calcium into bones to make them stronger and osteoclasts take calcium from bones. Exercise increases the rate that osteoblasts strengthen bones. Inactivity slow osteoblastic activity to weaken bones. So any exercise that places force on a bone will strengthen that bone.

If they live long enough, every woman and most men will suffer from osteoporosis. Women who break their hips from osteoporosis must have a hip replacement immediately. Otherwise, they have a 20 percent chance of dying from complications within a year. A study from Australia shows that running strengthens the leg bones of both older and younger women (Medicine & Science in Sports & Exercise, October 2005.) However, the research shows that bones used in an exercise are the only bones that are strengthened by that activity. So running strengthens leg bones, rowing strengthens arms and back, and lifting weights strengthen bones that are used for each lift.

More on osteoporosis

Wednesday, December 28, 2005

What's the best exercise to get rid of belly fat?

Sit-ups, crunches and other exercises can strengthen your belly muscles, but there is no such thing as spot reduction. Exercising a muscle does not get rid of fat over the specific muscles that are exercised. If it did, tennis players would have less fat in their tennis arms, but they don't.

When you take in more calories than your body burns, you store them as fat. You store more that half the fat in your body underneath your skin and over your muscles. Some people store fat primarily in their hips and are at low risk for heart attacks and diabetes, while others who store their fat primarily in their bellies are at increased risk for heart attacks and diabetes. The "ab" exercises can strengthen sagging belly muscles, but they will not remove extra fat from your belly. The only way to lose fat from the place where you store most of your fat (whether it's your belly or your hips) is to lose weight overall.

Tuesday, December 27, 2005

How can I avoid overtraining?

One of the most difficult problems for athletes is knowing when you are training too much. You make a muscle stronger only by stressing that muscle, feeling sore on the next day, and taking easy workouts or days off until the soreness goes away. Then you are supposed to take a hard workout again. If you do not feel soreness on the day after a hard workout, you have not injured your muscles, and they will not become stronger. However, if you try to work hard when your muscles feel sore, muscles do not recover and will feel sore all the time.

Every athlete knows that sometimes your muscles still feel little sore several days after a hard workout. You may think that you have recovered from your previous hard workout and you think you are ready to stress your muscles again. So you go ahead and try to run very fast and you start to feel sore all the time. Your joints, muscles and tendons ache. You feel tired. You can still run with the soreness in your muscles and tendons, but the soreness prevents you from running fast. Each succeeding day, the soreness increases and you think that you are sick, so you go to your doctor. He does a complete work-up and everything is normal, so you are stuck with a diagnosis of training too much.

Now you must go back to background training. If your sport is running, jog on the days that you can. Take days off when you feel sore. After several weeks, your muscle start to feel fresh again and you are able to start running. You are ready to start training again, but first you must promise yourself that you will never try to go hard when you feel soreness in your muscles and tendons. Set up a schedule in which you take a hard-fast workout, feel sore on the next day, and then go at an easy pace in your workouts until the soreness has completely disappeared.

Sunday, December 25, 2005

Does yawning serve any useful purpose?

During yawning, you breathe in deeply while you hold your facial muscles tightly contracted. Normally, you breathe 15 to 20 times a minute. When you feel tired, you may breathe only half as often, and may not get as much oxygen as you need, which causes nerve cells in your brainstem to make you breathe deeper and faster, and your facial muscles to contract in a yawn.

Breathing deeper and faster brings in more oxygen which refreshes you for a few seconds, but it also causes you to blow off more carbon dioxide from your bloodstream, which can make you feel dizzy and more tired. So yawing also can help put you to sleep, which is the most effective treatment for tiredness. After you nap, you can wake up feeling refreshed.

Saturday, December 24, 2005

Should blood pressure rise during weight-lifting?

Exercise raises blood pressure because pressure is determined by the force of your heart contracting times the resistance of the blood vessels against the flow of blood. When you exercise, your heart muscles contract with much greater pressure to increase blood flow to your exercising muscles. However, studies have shown that lifting heavy weights does not cause sustained high blood pressure.

Normal blood pressure is under 120 when your heart contracts and under 80 when it relaxes. When you lift a heavy weight, such as when performing a leg press, your blood pressure can rise from 120 over 80 to 400 over 200. When you run, your blood pressure can rise to around 200 over 80. However, within minutes after you finish exercising, your blood pressure returns to normal. Regular exercisers have lower blood pressures than people who do not exercise. However, if you have a weak heart or high blood pressure, check with your doctor before starting a weight-lifting program.

Friday, December 23, 2005

How much weight should I gain during pregnancy?

The optimal weight gain is 20 to 40 pounds. If a woman does not gain at least 20 pounds during pregnancy, she is at increased risk for having a small baby, which increases risks of birth defects and even death. However, if you gain too much weight, you are at increased risk for complications during and after childbirth.

What you eat is even more important than the amount of weight you gain. You should eat plenty of whole grains, beans, nuts and other seeds, and lots of fruits and vegetables. Limit refined carbohydrates (foods made from white flour, white rice or milled corn), restrict added fats, and avoid partially hydrogenated fats. Both mother and child need essential fatty acids that are classified into omega-3s and omega-6s. Pregnancy uses up fatty acids, particularly omega-3s. Several recent studies show that post-partum depression may be caused by low levels of omega-3 fatty acids. Essential fatty acids are found in all seeds, including nuts, beans and whole grains, but not in refined flour used for most bakery products and pastas. Partially hydrogenated fats deplete the body of omega-3 fatty acids and should be avoided. Pregnancy also depletes folic acid, and a deficiency can cause birth defects. Folic acid is found in leafy greens, whole grains, nuts, seeds and beans. Folic acid supplements are recommended for most pregnant women.

More on Omega-3's and post-partum depression

Thursday, December 22, 2005

How can I keep from losing height as I age?

The bones of your spine are separated by pads called discs. As you age, these discs dry out and become smaller. However, regular exercise compresses and relaxes these discs as you move up and down. This helps to keep the discs from shrinking and maintains your height. Regular exercise also helps to strengthen bones and keep them from bending or being crushed. One study from Israel showed that people who exercise regularly lose only half as much height as people who never exercise -- just 2.6 centimeters compared with 5.5 centimeters. If you have not already started exercising to prevent heart attacks, diabetes, high blood pressure, high cholesterol and loss of mental function, and just to keep you feeling good, you should exercise to help you stand taller as you age.

Wednesday, December 21, 2005

Are soybeans healthful or unhealthful?

All plants contain chemicals that are healthful and chemicals that can harm us. Fortunately for us, our ancestors learned which plants are edible and healthful, and taught us to avoid those that are poisonous to humans. However, if you eat very large amounts of one food, you can poison yourself, even though reasonable amounts are harmless or beneficial.

For example, soybeans contain genistein, a weak estrogen that may help to prevent breast cancer. They contain omega-3 fatty acids that help prevent heart attacks, and are loaded with fiber that helps to prevent diabetes. But they also contain small amounts of trypsin inhibitors that increase risk for pancreatic damage and cancer in animals. Hemagglutinins in soybeans could cause clots to form and travel to the lungs. Goitrogens in soybeans block thyroid function to increase your need for that hormone. Estrogen-like genistein in soybeans could stimulate immature lobules in breast tissue of infants to increase risk for breast cancer many years later. Phytates in soybeans and many other plants can block the absorption of minerals.

However, you would need to eat very large amounts of soy products to get any of these negative effects. Enjoy a moderate amount of soy foods, but do not let health claims lead you to eat huge amounts of soy to the exclusion of other foods. A healthful diet is a varied diet.

More on the soybean controversy

Tuesday, December 20, 2005

Can I return to running after a knee injury?

A study from East Germany shows that athletes who tear the anterior cruciate ligament (ACL) in their knees will have permanent knee damage if they return to competitive sports (Arthroscopy, June 2005). The anterior cruciate ligament runs from the top bone of the knee to the bottom one and prevents the top bone from sliding forward when the foot hits the ground during running and walking. If it is torn, the knee becomes so unstable that a person will have difficulty walking, so all torn anterior cruciate ligaments must be repaired.

In this study, East German Olympic athletes who tore their knee ligaments in 1963-1965, and returned to competition after having their ligaments repaired, were examined 10 and 20 years later. Virtually all had severe knee cartilage damage and more than half had total knee replacement surgery.

Athletes with repaired torn ACLs probably should never run or jump again, although they may be able to pedal a bicycle. Another study showed that people who have broken cartilage in their knees can walk and cycle, but should not run or jump.

To keep your bones from wearing down at the joints, their ends are covered with a thick white gristle called cartilage. Even one bleed into a joint damages its cartilage forever. Doctors cannot replace or heal broken cartilage, they can only replace entire knee joints. Operating and removing broken cartilage probably increases a person's chances of needing a knee replacement, particularly if the exerciser continues to run and jump. Shearing forces on the knee are very great during walking downhill and running, and minimal during walking on level ground and cycling. So people who have ever damaged cartilage in their knee should walk on level ground, swim or cycle, and avoid running and jumping.

More on knee surgery

Monday, December 19, 2005

Will vigorous exercise help to prevent osteoporosis?

A woman’s bones are strongest when she is twenty years old. After that, she continues to lose bone for the rest of her life, and for the first few years of menopause, the rate that she loses bones more than triples. A study from the University of Erlangen in Germany shows that vigorous exercise during the menopause helps prevent osteoporosis (Archives of Internal Medicine, May 24, 2004). In this study, fifty women lifted weights in group training sessions twice a week, and exercised by themselves twice a week. They also took calcium and vitamin D. As their muscles became stronger, so did their bones. Their blood cholesterol levels dropped significantly and they complained far less about muscle and joint pains. This study shows that strengthening muscles also strengthens bones and that women who exercise vigorously in later life may have less muscle and joint pain.

Other studies have shown that women can benefit from a strength training program at any age to prevent osteoporosis or slow its progression. Join a gym that has weight-training machines and pick six to ten of the machines. Have the instructor help you select the appropriate weights and teach you how to use the machines properly. Do a set of eight movements in a row on the first machine, rest a few seconds and then do two more sets of eight. Do this on each of the machines. Repeat the routine two or three times a week. It's never too late to start.

Sunday, December 18, 2005

I feel tired all the time; will iron pills help?

You should not take iron pills without a specific diagnosis. Several studies have shown that iron deficiency can be healthful. Before the bad LDL cholesterol can form plaques in arteries, it must be converted to oxidized LDL and iron causes this reaction. Lack of iron reduces your chances of forming plaques in your arteries and suffering heart attacks and strokes.

Less than 50 percent of the iron in your body is in your red blood cells. Most iron is in your iron reserves in your liver, spleen and other tissues. Your body needs iron to make red blood cells and if your body does not contain enough iron, you will become anemic, but you will not become anemic until you have depleted all your iron reserves. You can be iron deficient but not anemic when you have an adequate supply of red blood cells, but no iron reserves. Iron deficiency does not make you tired unless you are also anemic, but it can tire athletes exercising at their maximum.

Blood iron levels are parts of routine blood tests. If your blood iron levels are low and you are not anemic, you need a special test called ferritin to measure iron reserves. If your ferritin is low, your doctor will look for a source of bleeding such as heavy menstruation or through your intestinal tract. If no serious source is found, you need no treatment unless you are a highly competitive athlete.

More on chronic fatigue

Saturday, December 17, 2005

Do competitive athletes have a greater chance of developing arthritis than non-athletes?

Yes; former champion athletes are at higher risk for degenerative arthritis requiring eventual hip and knee replacements, but that doesn’t mean that you should stop exercising. Champion athletes often train through pain and compete when they are injured. You should never do that. Your body talks to you. If your hip or knee hurts when you exercise, stop exercising. If the pain returns every time that you run, stop running and find another sport.

Most former athletes who end up with joint replacement surgery had major injuries that came from training when they should have rested, or from traumatic injury that damaged cartilage. Damaged cartilage never heals. Most people who have damage to the cartilage in their hip or knee joints should stop running and jumping, because the impact when their feet hit the ground is transmitted up to break more cartilage. Relatively safe hip and knee exercises include cycling and swimming; they are done with smooth rotary motions without road shock, or in the water that protects the joints. When the pain in your knee is so bad that it prevents you from sleeping, it may be time to get a knee replacement.

If you have multiple joint pains, read about Reactive Arthritis

Friday, December 16, 2005

Will I get stronger by lifting heavier weights or doing more repetitions?

In a study from Yokohama University in Japan, one group of athletes was asked to do low-intensity muscle contractions 3600 times in a row. Others were asked to lift very heavy weights 12 times. There was some muscle damage in the people who contracted their muscles 3600 consecutive times, but this damage was far less than from lifting a very heavy weight 12 times in a row. This shows you that lifting a heavy weight causes much more muscle damage than lifting light weights continuously for a long time. And this means that you will become far stronger from lifting very heavy weights a few times than from lifting light weights many times.

When you lift a heavy weight to the point where your muscles start to burn, you are causing considerable muscle damage. Then you feel sore on the next morning and perhaps for several days. When the soreness goes away, your muscle has healed and is stronger than it was before you damaged it. Since you get more damage from lifting heavy weights a few times than from lifting light weights many times, you get a greater gain in strength from lifting heavier.

If you want to become very strong, first check with your doctor to make sure that you have no health problems that will be aggravated by hard exercise. Then spend several weeks lifting weights lightly. After you have been lifting lightly for at least a couple of months, you can start training. Pick five or six exercises and find the heaviest weight for each that you can lift ten times in a row. You should struggle to finish the last four or five lifts of a set of ten. The soreness means that you are tearing your muscle fibers. Then add a few pounds and ask your friends to lift the weight so you can lower it slowly six times. Then add a few more pounds and lower this weight for a set of three. If you feel that the weight is too great or that you are losing control of the weight, ask your friends to take the weights from you immediately.

This type of lifting will cause a great deal of pain while you lower the weight and a lot of pain the next morning. As long as you don't injure yourself, this is good because you need muscle damage to become stronger, and pain and soreness are signs of muscle damage. Do not lift for a couple of days, so you can allow your muscles time to heal. When they are no longer sore, do an easy workout of lifting weights that are so light that you do not have to struggle and you feel comfortable. Try to do three sets of 10 for each exercise.

Two days later repeat the same easy workout. Seven to ten days after your hard workout, try another heavy workout, but only if the soreness has gone completely from your muscles. Each week, try to do a hard workout, take two days off, then do easy workouts every other day and when the soreness is gone, attempt to lift heavy again. You will be amazed how strong you will become. This type of training is very hard on your body, so you can be hurt by it and should not attempt such workouts if you have heart or blood pressure problems.

Wednesday, December 14, 2005

Hypothermia and Frostbite

Hypothermia is a sudden drop in body temperature that can kill you. If you dress properly and exercise vigorously enough, it should never happen to you. Your body sends you signals as your temperature starts to drop. With a one degree drop in temperature, your speech becomes slurred. This, in itself, is not dangerous, and occurs when people stay out in temperatures below 35 degrees, but it serves as a warning that you are losing more heat than your body is producing. To protect yourself, you can produce more heat by exercising harder or you can conserve heat by adding more layers of clothes. With a drop of three degrees, you'll find it difficult to coordinate your fingers. Seek shelter immediately. When your temperature drops five degrees, you won't be able to walk and you'll stumble and fall and not be able to get up. Then you may not be able to get out of the cold and your body temperature can continue to drop rapidly and you can die. If your clothes are wet, your temperature will drop even faster. Take the warning signals seriously; if you have slurred speech or difficulty using your hands, take action or you may not get another chance.
Frostbite means that your skin is frozen. You have plenty of warning before that happens. Your normal skin temperature is around 90 degrees. As your skin temperature starts to drop, blood vessels close and your skin turns white. When the temperature reaches 59 degrees, your body attempts to rewarm your skin by opening the blood vessels, causing your skin to tingle, itch, burn and turn red. When this happens, get out of the cold. If you don't, the blood vessels in your skin will close down again and your skin temperature can drop below 30 degrees and start to freeze.

Tuesday, December 13, 2005

Should I eat while I exercise?

If you are going to exercise for more than an hour, you can increase your endurance by eating every 15 to 20 minutes. A feeling of general tiredness during exercise is usually caused by low levels of stored sugar in your liver, while a feeling of muscle fatigue is usually caused by low levels of stored muscle sugar.

Your brain gets more than 98 percent of its energy from sugar flowing to it in the bloodstream, but there is only enough sugar in your bloodstream to last for three minutes. Your liver must constantly release sugar from its cells into your bloodstream. However, there is only enough energy in your liver to last about 12 hours without replenishment.

Your muscles get their energy from many sources: sugar and fat stored in them, and sugar, fat or protein in the bloodstream. When your muscles run out of their stored sugar supply, they can hurt and feel tired. You can increase endurance by eating frequently, and you can eat whatever you like: nuts, fresh or dried fruits, chicken, sandwiches or anything else. The amount of sugar you get in sports drinks is not adequate to support strenuous exercise for long periods of time.

Monday, December 12, 2005

Is it inevitable that I will lose muscle as I age?

With aging, it takes more effort and time to walk up stairs, mow the lawn, fix a faucet or wash the dishes. Tasks that you did without effort when you were younger can become major ordeals that leave you exhausted when you are older. Dr. Jerome Fleg, a cardiologist at the National Heart, Lung, and Blood Institute, tested 800 men and women over several years and found that their ability to sustain exercise decreased rapidly as they aged. The older they became the faster they lost what researchers call aerobic capacity (Circulation, July 26, 2005). Aerobic capacity is a measure of your ability to use oxygen to do work. If your body can process more oxygen than that of another person, usually you will be able to run faster, walk or work longer, and have more energy than that person. The men and women lost three to six percent per decade in their 20's and 30's , and 20 percent per decade in their 70's. The men lost aerobic capacity faster than the women. The men lost 8.3 percent of aerobic capacity in their 40's and 23 percent per decade in their 70's.

This study was done with people who were healthy enough for vigorous exercise on a treadmill that measured their exercise capacity. People who have had heart attacks, strokes, diabetes or other wasting diseases would lose aerobic capacity much faster than healthy people. The results showed that a regular exercise program can increase exercise capacity by up to 25 percent, which would give the older participants the same exercise capacity as you would expect in people who are twenty years younger.

The loss of aerobic capacity with aging explains why older people cannot compete effectively against younger ones in endurance events. The good news is that a regular exercise program can increase your maximum heart rate. By exercising regularly and vigorously, your will develop stronger skeletal muscles. When you contract your leg muscles, they squeeze against the veins in your legs and pump blood toward your heart. When your leg muscles relax, the veins dilate and fill with blood. This alternate contacting and relaxing pumps extra blood toward your heart. The extra blood returned to the heart stretches and strengthens the heart muscle, causing it to beat faster and with more force. So strengthening your leg muscles increases your maximum heart rate, even as you age.

Sunday, December 11, 2005

Why do I get goosebumps on my skin?

In prehistoric times, goose bumps may have helped humans frighten their enemies. Now they’re not much use. The hairs on your body lie close to your skin and have small muscles attached to them called arectores pilorum. When you feel cold or are frightened, these muscles pull on the hairs so they stand out almost perpendicular to your body, causing small bumps to appear. Hairs trap air between them in the same way that the fibers in a sweater trap air, helping to keep you warm. The arectores pilorum muscles also press against the oil glands located at the base of each hair shaft and squeeze oil onto the surface of the skin. The oil covers the skin's surface and helps to keep the skin warm by reducing evaporation of sweat from the skin's surface.

Many thousands of years ago, people had more body hair and fewer clothes. Contraction of arectores pilorum muscles caused hair to stand on end, making a man appear larger than he was. Today, our greatest adversaries are other people, and goose bumps may reveal that you are scared. Now most people hide their goosebumps with clothes.

Saturday, December 10, 2005

Will exercising without a bra make my breasts sag?

Women can wear bras when they exercise if they want to, but there is no medical evidence that exercising braless will harm them or cause breasts to sag.

A breast is made up of skin on the outside, fat underneath and muscles under that. Breasts are held in place by skin and small ligaments that go from the skin to muscles underneath the breasts. The intermittent stretching that occurs during exercise does not stretch out the skin or ligaments.

Since breasts is composed mostly of fat, when a woman exercises, she loses fat from her breast as well as the rest of her body, so they become smaller and may appear to sag. Sagging is determined to some degree by heredity. All women develop some sagging as they age and those with the largest breasts are the ones who are most likely to develop sagging.

Most women with small breasts prefer not to wear bras when they exercise. However, some women with large breasts may need them to feel more comfortable. If a woman wants to wear a bra, she should choose one that is loose enough to let her breathe comfortably, and tight enough to keep the breasts from bouncing and the bra from riding up or twisting during exercise.

Sports bras are designed specifically to hold the breasts firmly against the chest without binding. Many runners, dancers and others who bounce a lot during their exercise will find sports bras most comfortable. Bras with underwires often give good support, but the bra should not have bones or wires that dig into the body or seams or hooks that rub against the skin.

Since women don't need to wear a bra during exercise, they should wear them only if they want to.

Friday, December 09, 2005

What can I do about excessive gas?

Carbohydrates are made of sugars either alone or in combinations (starches) and before they can be absorbed, they must be broken down into single sugars. Vegetables, beans, nuts, cereals and other foods contain starches and sugars that should be absorbed in the upper intestinal tract. However, some of the carbohydrates cannot be broken down. If they are not absorbed in the intestines, they pass to the colon where bacteria ferment the carbohydrates to release gas.

Half of the world's population develops gas and cramping after drinking milk because they lack the intestinal enzyme that is necessary to break down the double sugar in milk called lactose. If lactose is not absorbed in the upper intestinal tract, bacteria ferment it in the colon to release gas. If you are lactose intolerant, you can avoid dairy products, but no one should avoid vegetables, beans and whole grains.

If you are bothered by gas when you eat beans, whole grains or vegetables, you may not have an adequate colony of friendly bacteria in your colon to break down the resistant starches in plants. If you have recently changed your diet to include more of these foods, give yourself a few weeks or even months to build up the bacteria you need to digest them without excessive gas. Recent research shows that normal intestinal bacteria make up approximatly 95 percent of the total number of cells in the human body. The good bacteria help to prevent bad bacteria from infecting you, and may help to prevent intestinal diseases such as ulcerative colitis, Crohn's disease or cancer.

If you have waited a reasonable time and are still bothered by excessive gas, check with your doctor. One study showed that Rifaximin, an antibiotic that cannot be absorbed from the intestines, can control many cases of excessive intestinal gas. However, this antibiotic is not available in North America; ask your doctor about using metronidazole instead.

Thursday, December 08, 2005

What's the best way to treat dry skin?

Dry skin means lack of water, not lack of oil. 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. All lotions and creams work the same way, no matter how much they cost or what special ingredients they claim to contain.

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 externally applied chemicals. The longer skin is immersed in water, the more protective outer coatings of skin is stripped off.

A study from Denmark shows that daily use of some skin creams can make the skin even more sensitive to irritants such as soaps and alcohol. The researchers asked people to apply either a high or low-fat moisturizing cream on the upper arm, three times a day, for five days, while the other upper arm served as a control. The day after moisturizer treatment was stopped, the researchers applied an irritant called sodium lauryl sulphate to the creamed arm. The high-fat creamed arm had far more redness and irritation, while the low-fat creamed arm had no irritation. This shows that some high-fat moisturizing creams can strip away the protective outer layer of skin called the epidermis and cause skin rashes. If your moisturizing cream appears to irritate your skin, you may benefit by substituting a low-fat cream that does not leave a greasy layer when you rub it on.

Wednesday, December 07, 2005

If I avoid all foods that contain cholesterol, will my high cholesterol return to normal?

No. Your blood cholesterol level is influenced far more by how many calories and how much saturated and partially hydrogenated fat you eat, than by how much cholesterol is in your food. Cholesterol is found only in foods from animals, such as meat, fish, chicken, dairy products and eggs. It is not found in plants. More than 80 percent of the cholesterol in your body is made by your liver. Less than 20 percent comes from the food that you eat. When you eat more cholesterol, your liver makes less.

Your liver makes cholesterol from saturated fats, which are found in most foods but are concentrated in meat, poultry and whole-milk dairy products. The saturated fat is broken down by your liver into acetone units. If you are not taking in too many calories, your liver uses the acetone units for energy, but if you are taking in more calories than your body needs, your liver uses these same acetone units to manufacture cholesterol. That explains why eating two eggs a day does not raise blood cholesterol levels in the average American. They are already taking in so much cholesterol from meat, fish and chicken and diary products, that when they take in more, they absorb less.

The average North American takes in 350 mg per day of cholesterol. If he takes in 26 mg per day, he absorbs 41 percent. When he takes in 188 mg cholesterol per day, he absorbs only 36 percent, and when he takes in 421 mg per day (the equivalent of two eggs), he absorbs only 25 percent. Some people absorb more than five times as much as other people at the same intake. So you lower blood cholesterol levels far more effectively by eating less food, less saturated fat and less partially hydrogenated fats than by avoiding foods that contain cholesterol.
DASH Diet to lower blood pressure AND cholesterol

Tuesday, December 06, 2005

What's "background and peaking"?

Knowledgeable competitive athletes plan their training programs months in advance, using a technique called background and peaking. First they spend many months in background training, in which they work out for long hours, mostly at low intensity, followed by a shorter period of peaking training in which they do far less work, but at a much greater intensity.

A distance runner may run 100 miles a week during his winter background training. A few months before her most important racing season, she reduces her workload to around 40 miles a week, but she runs almost as fast as she can two or three times a week.

In his background period, a weight lifter lifts many tons of lighter weights. As he gets closer to his main competitive season, he takes workouts in which he lifts very heavy weights, but does far fewer repetitions. In his background period, a shot putter lifts tons of lighter weights each week and throws mostly for form, not distance. Then as he gets into his season, he does far less lifting, but with heavier weights. He also spends one day a week throwing as far as he can. You can do the same. Start your exercise program at low intensity and low volume. Gradually increase your workload for several months before you try to run fast, lift heavy or exercise intensely.

Monday, December 05, 2005

What would cause dizziness in a very fit athlete?

Athletes and other very fit people may feel dizzy when they rise from lying to standing because of their slow pulse rates. Exercise makes your heart stronger so it can pump more blood with each beat and it doesn't have to beat as often. A slow pulse rate can be good. Since your heart doesn't beat as often, it has more time to rest between beats. Like a low-mileage used car, perhaps this will mean it takes longer to wear out. But a slow heart rate can make you dizzy when you change position.

When you raise yourself from lying to sitting, or from sitting to standing, the force of gravity pulls blood down from your brain towards your feet and your blood can't get back to your brain until your next heart beat. If you have a pulse rate of only 50 beats a minute, it will take more than a second between beats. That can be enough time for your brain to suffer briefly from a lack of oxygen, so you feel dizzy. You can even pass out while you wait for your next heartbeat to come along and pump blood back up to your brain.

Dizziness can also be a sign of an irregular heartbeat or blocked arteries leading to your brain, so people who feel dizzy when they get up should check with their doctors. If they are athletes, chances are that they only have a strong athletic heart with a slow rate, and all they need to do is remember to get up slowly.

Sunday, December 04, 2005

What causes hot flushes at menopause?

Hot flushes are caused by a down-setting of the temperature-regulating part of the brain. When you have an infection and your temperature rises above 100 degrees, you sweat to cool off. At the time of the menopause, you still sweat when your temperature rises, but at lower than normal temperatures, such as when you go from 97 to 98 degrees. Hot flushes persist for five years in 60 percent of women and for more than 15 years for ten percent.

A hormone called norepinephrine causes a woman's brain to think that her body is overheating, even if it isn't. She then flips open the blood vessels in her skin, giving her the feeling of a rush of heat, and she starts to sweat. Clonidine, a blood pressure medicine, lowers norepinephrine and blocks hot flushes in some susceptible women. We still do not have any good drugs to effectively lower norepinephrine levels in the brain, but here at least is a lead for future researchers.

Saturday, December 03, 2005

How can I get the most from my warm-up?

Warming up before you exercise helps to prevent injuries and lets you jump higher, run faster, lift heavier or throw further. Your warm-up should involve the same muscles and motions you plan to use in your sport. For example, before you start to run very fast, do a series of runs of gradually-increasing intensity to increase the circulation of blood to the muscles you will be using.

Muscles are made up of millions of individual fibers, just like a rope made from many threads. When you start to exercise at a very slow pace, you increase the blood flow to muscle fibers, increase their temperature, and bring in more oxygen, so the muscles are more pliable and resistant to injury. When you contract a muscle for the first time, you use less than one percent of your muscle fibers. The second time you bring in more fibers, and you keep on increasing the number of muscle fibers used in each contraction for several minutes of using that muscle. It’s called recruitment. When you are able to contract more muscle fibers, there is less force on each individual fiber to help protect them from injury. Usually you are warmed up when you start to sweat.

The same principle applies to your heart. Angina is a condition in which the blood vessels leading to the heart are partially blocked so the person has no pain at rest, but during exercise, the blocked arteries don't permit enough blood to get through to the heart muscles, causing pain. If people with angina exercise very slowly before they pick up the pace, they are able to exercise longer and more intensely before they felt heart pain. Always check with your doctor if you feel any heart pain during exercise.

Competitive athletes in sports requiring speed and endurance perform better after they warm up with increasing intensity. Warming up slowly does not increase the maximum amount of oxygen that you can bring to muscles that you need during competition. If you are a runner, skier, cyclist, or an athlete in any sport that requires endurance, warm up at a gradually increasing pace. Use a series of increasingly intense repetitions of 10 to 30 seconds duration, with short recoveries, until you are near your maximum pace. This type of warm-up increases endurance because intensity increases the maximum amount of oxygen that you can bring to your muscles, as you continue to compete, and lets your muscles contract with greater force as you begin to fatigue. You will then be able to bring in more oxygen to your muscles than you could have done without the intense warm-up.

Friday, December 02, 2005

What can I do to correct chronic constipation?

Check with your doctor who will usually order thyroid tests and a barium enema to rule out obstruction. Most of the time, these tests will be normal and you suffer from a faulty diet. The pain of constipation is usually caused by gas stretching your colon where it has been blocked by hard stool. Food is turned into a soup in your stomach and remains that way until it reaches your colon, where water is absorbed and stool is formed. If you don't drink enough fluid or eat enough fiber, the stool rapidly turns into hard pieces that are difficult to pass. Low-fiber foods, such as breads, rolls, pastries, bagels, pretzels, noodles and pasta cause hard stools, while eating fiber-rich foods, such as fruits, vegetables, whole grains and beans, keep everything soft.

If you drink lots of water and eat lots of fiber and are still constipated, you may have nerve damage and need to be checked for diabetes or other causes. Laxatives and fiber supplements offer little help, but your doctor may prescribe other drugs, such as the antibiotic, erythromycin; the gout medicine, colchicine; or the stomach medicine, Prevacid, which may be helpful in some cases of chronic constipation.

Irritable Bowel Syndrome

Thursday, December 01, 2005

Is regular tea as good for your heart as green tea?

Probably. Several studies show that people who drink green tea have a reduced incidence of heart attacks. Since black tea is made by fermenting green tea leaves, you would think that green tea and black tea would be the same, and they may be. But almost all studies on tea and heart attacks have been done with green tea, probably because green tea companies support and publicize the studies. Both green and black tea contain potent antioxidants: flavinoids, polyphenols and catechins. These antioxidants block cox-2 enzymes that cause clots and block arteries. Scientists do not recommend tea to prevent heart attacks yet because there may be other variables. Tea drinkers may have fewer heart attacks because they have healthier lifestyles for other reasons.