Sunday, April 30, 2006

What causes "bonking" ?

If you watch a major bicycle race on TV, you have to be impressed by how the riders can eat enough to sustain them through races that require more than five hours of near maximum effort. If they do not get enough food during their ride, they can fall off their bikes, lie on the ground unconscious and start to shake all over in a in a massive convulsion. This is called bonking: passing out from low blood sugar.

Your brain gets almost all of its fuel from sugar in your bloodstream. When your blood sugar level drops, your brain cannot get enough fuel to function properly, you feel tired and confused and can pass out. There is only enough sugar in your bloodstream to last three minutes. To keep your blood sugar level from dropping, your liver must constantly release sugar from its cells into your bloodstream, but there is only enough sugar in your liver to last 12 hours at rest. During intense exercise, your muscles draw sugar from your bloodstream at a rapid rate. Your liver can run out of its stored sugar and your blood sugar level can drop, and you bonk.

Bonking is common in bicycle races if a rider does not eat frequently, but is rare in long distance running races. When you run, your leg muscles are damaged from the constant pounding on the roads and you must slow down. However, you pedal in a smooth rotary motion which does not damage your muscles, so you can continue to pedal at a rapid cadence for many hours.

To prevent your blood sugar from dropping too low during intense exercise lasting more than two hours, eat at least every 15 minutes. It doesn't matter what you eat: salted peanuts, a peanut butter and jelly sandwich, chicken, an apple, a banana or anything else. Almost all fit people can take small amounts of food frequently during exercise without developing stomach cramps.

Friday, April 28, 2006

Are cortisone injections into joints safe?

Doctors often inject cortisone-type medications into painful damaged joints and tendons. Single injections can relieve pain and swelling and appear to be safe, but many studies show that repeated injections can damage joints and delay healing. Most doctors will recommend having no more than three injections into the same joint in a lifetime.

Athletes and exercisers often experience pain from injuries to their tendons, muscles, fascia or ligaments. When an injury heals in a few days, no treatment is indicated, but sometimes they persist for months, particularly in the fascia on the bottom or back of the heel, in the large tendon in the back of the lower leg, or in the tendons on the elbows or shoulders. Cortisone-type drugs reduce swelling and lessen pain and can allow an athlete or exerciser to get back to sports, but cortisone injections can weaken the tendons for several months.

If you suffer pain in tendons, muscles, ligaments or fascia, check with your doctor to see if you have a treatable chronic disease causing it, such as hepatitis or reactive arthritis. Non-steroidals that are usually prescribed can help to block pain but do not heal damaged tissue. If you receive a cortisone injection, make sure that you protect that area from hard exercise for at least two months.

Thursday, April 27, 2006

Will HDL injections cure blocked arteries?

Thirty years ago, researchers showed that a family living in a northern Italian town lived to be very old and were extraordinarily resistant to heart attacks. These people were unusual because they had extremely low blood levels of the good HDL cholesterol that prevents heart attacks. The researchers found that their HDL cholesterol was much denser and had much larger particles than the normal HDL cholesterol, and did a better job of clearing cholesterol from the bloodstream. They concluded that the special HDL, which they called HDL-Milano, is so much more effective that these people don't need very much to prevent arteriosclerosis.

Before the discovery of HDL-Milano, researchers would not waste their time trying to give HDL infusions to prevent heart attacks because they could not patent a biological product and therefore could not make any money from their experiments. However, HDL-Milano is a specific, patentable product. The next step was to copy HDL-Milano and infuse it into people with plaques in their arteries, and show that their plaques became smaller. That has been done (Journal of the American Medical Association, November 4, 2003).

However, it will be at least six years before HDL-Milano treatments are available to the public. For now, eat lots of plants, avoid smoking and being overweight, restrict saturated fats and partially hydrogenated fats, and exercise regularly. Then you won't ever need the HDL-Milano by intravenous infusion.

Modified DASH Diet

Wednesday, April 26, 2006

Is baldness in women linked to heart attacks?

Male-pattern baldness is very common in men and fairly common in women. Male pattern baldness may be caused by high blood insulin levels caused by eating large amounts of refined carbohydrates. It is associated with high insulin levels and an increased risk for heart attacks in women as well as in men (Dermatology Online Journal, November 2005). Although not an established treatment, you may be able to halt further hair loss, AND reduce your risk for heart attacks, by eating a diet that is low in refined carbohydrates.

More on Baldness and heart attacks
Treatments for baldness

Monday, April 24, 2006

What causes muscle cramps during competition?

If you've ever developed severe muscle cramps during long-term exercise, the odds are that you never found out why it happened. Doctors in South Africa studied triathletes and found that most of the time, the muscles cramps were not caused by dehydration, thyroid disease, blocked blood flow, nerve damage, or mineral abnormalities of calcium, sodium, magnesium or potassium (Medicine & Science in Sports & Exercise, July 2005).

The athletes with cramps had normal electrolytes and did not lose more fluid during exercise than those who did not suffer cramps. The researchers showed that the most likely cause is muscle fatigue or tearing of the muscle itself. Electromyograph (EMG) studies at one to five minutes showed markedly elevated electrical activity of the nerves controlling the cramped muscles. Therefore muscle cramps during long distance athletic events appeared to be caused by exercise-induced damage to the muscles themselves. If this is true, muscle cramps during endurance events can be prevented by slowing down when you feel excessive soreness in one muscle group or straining in a muscle. Of course, competitive athletes will not do this, and they pay for it with muscle cramps.

Lack of salt is a common cause of cramps in exercisers. You'll find lots of other reports to help you get the most from your exercise in the Fitness section of DrMirkin.com

Sunday, April 23, 2006

Will training for a triathalon make me a better cyclist?

World-class triathletes are slower runners, swimmers and cyclists than athletes who compete in only one sport. A study from the University of Toulon-Var in France shows that swimming before cycling slows you down (Canadian Journal of Applied Physiology, August 2005). Well-trained male triathletes pedaled for 30 minutes on a stationary bicycle at 75 percent of their maximal aerobic power, with a cadence of 95 revolutions per minute. Later they did the same exercise after swimming 1500 meters.

After swimming, they had a 13 percent reduction in efficiency, and significantly higher blood lactate levels. Fatigue from swimming caused them to lose their efficient form so that they had to work much harder to maintain the same pace. Fatigue has the same effect on all athletes. A fresh field goal kicker in football will perform better than one who has played the entire game. Triathletes will always swim, run and cycle slower than comparable athletes training for only one sport. However, triathletes have fewer injuries.

Friday, April 14, 2006

Why are diabetics at such high risk for heart attacks?

A recent study from Washington University in St Louis may explain why more than 75 percent of diabetics die of heart disease (Journal for the American College of Cardiology, February 7, 2006). The heart muscle of diabetics uses a much higher percentage of fat for energy than that of non-diabetics, to markedly increase risk for heart attacks.

The energy source for heart muscle is mostly sugar and fat, and to a lesser degree, protein. Muscles need far more oxygen to process fat than to process sugar. The blood supply to heart muscle comes from large arteries on the outside of the heart. Diabetics have narrowed arteries because high blood sugar levels cause plaques to form and reduce the diameter of the coronary arteries. The increased need for blood flow from burning fat and the decreased blood flow from narrowed arteries put diabetics at very high risk for heart attacks, heart failure and sudden death. The increased use of oxygen increases blood levels of oxidants that further damage the inner linings of arteries.

Type 2 diabetes can be prevented
If you are already diabetic, please read about treatment of insulin resistance

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Thursday, April 13, 2006

Do I need salt during exercise?

When you exercise for more than three hours, you should take in salt as well as fluids. A study from Switzerland followed female competitive distance runners who took in drinks with different concentration of salt during a four hour run. Ninety-two percent of those who took in plain water with no additional salt developed low blood levels of salt, which can be dangerous (British Journal of Sports Medicine, Volume 37, Issue 4, 2003).

Taking in fluid without also taking in adequate amounts of salt dilutes the bloodstream, so that the concentration of salt in the blood is lower than that in brain cells. This causes fluid to move from the low-salt blood into the higher-salt brain causing the brain to swell which can cause seizures and death. Taking in extra salt during prolonged exercise increases thirst so you drink more fluids, and prevents blood salt levels from dropping so low that you become tired, develop muscle cramps, and can even die. Furthermore, without salt you do not recover as quickly and are more likely to be injured or tired all the time.

If you're concerned about the reports of deaths from over-hydration, read about hyponatremia

Wednesday, April 12, 2006

Which burns more calories, running or cycling?

The standard comparison is that one mile of running equals four miles of cycling, but that's lousy science. Although running requires the same amount of energy per mile at any speed (110 calories per mile), riding is affected by wind resistance so the faster you ride, the more energy you use. So you have to compare running and cycling at different cycling speeds.

Dr. Edward Coyle of The University of Texas in Austin determined average values of oxygen consumption by cyclists to develop a table to estimate the approximate caloric equivalence between running and cycling. He found that if you ride 20 miles at 15 mph, you burn 620 calories (20 miles X 31 calories per mile = 620 calories). Take the 620 calories and divide them by 110 calories per mile for running and you get 5.63 miles to burn the same number of calories. So riding a bicycle 20 miles at 15 miles per hour is equal to running 5.6 miles at any speed.

Dr. Coyle made the calculations easy by providing conversion factors for different riding speeds: 10MPH=4.2, 15MPH=3.5, 20MPH=2.9, 25MPH=2.3, and 30MPH=1.9. Divide the number of miles ridden by the conversion factor for your riding speed to tell you the equivalent miles of running at any speed. Thus, for 20 miles ridden at 10MPH, divide 20 miles by 4.2 which tells you that your ride is equivalent to 4.8 miles of running. This formula is for an average-size adult (approximately 155 pounds). A larger cyclist would divide by a slightly higher number; a smaller cyclist, by a slightly lower one. Wind and hills are not accounted for in the table; nor is drafting (riding behind another cyclist), which can reduce your energy expenditure by up to one-third.

Tuesday, April 11, 2006

How can I prevent stress fractures?

Stress fractures, small cracks on the surface of the bones, usually start out as a minor discomfort in the foot or leg that occurs near the end of a long run. Usually the pain goes away as soon as the athlete stops running. On the next day, the pain returns earlier in the run. If she notices that it hurts to touch just one spot on a bone and then stops running for a week, she can return to running quickly, but usually she ignores the pain and develops a full- blown stress fracture that hurts all the time. She now has to avoid the hard pounding of running, but can ride a bike or swim for exercise until the fracture heals in 6 to 12 weeks. The most common sites for stress fractures are the bones in the front of the feet or the long bone of the lower leg, but running can cause stress fractures anywhere, even in the pelvic bones.

Forty-five percent of competitive female runners develop stress fractures. The women most likely to suffer these injuries are those who restrict food and those who have irregular periods. Restricting food can stop a woman from menstruating regularly, which can stop her body from producing the female hormone, estrogen. Lack of estrogen weakens bones. Exercise does not cause irregular periods, but not taking in enough calories can. Women who stop menstruating when they exercise heavily will usually start to menstruate regularly when they eat more food. I often prescribe bone strengthening medications such as Fosamax or Evista to women with stress fractures that do not heal in six months.

Treatment of other common sports injuries

Monday, April 10, 2006

I'm too skinny; how can I gain weight?

Weight gain should always be in the form of muscle, not fat. To build muscle, start a weight-bearing exercise program. Go to a gym and learn how to do the weight training circuit. It only takes 15 extra grams of protein a day to build a pound of muscle a week -- so you really won't need to eat a lot more. Muscle is far more dense than fat. Once you are exercising regularly and gaining muscle, your appetite will probably increase and you will eat more without any conscious effort. Most muscular people and heavy exercisers will eat plenty to meet their calorie needs. The training tables for football teams are piled high with every kind of food.

It's never too late to start a weight training program. Underweight older people look and feel frail because they have lost most of their muscles, not because of lack of fat. If you are inactive, you lose muscle mass to the point where you are unable to carry out daily activities -- climbing stairs, getting up out of a chair -- because your muscles are not strong enough to move the weight of your own body. Don't try to add fat to a weak body. Overweight older people often have the double burden of weak muscles AND 20, 40 or more extra pounds to lug around with them every day.

Sunday, April 09, 2006

Can a high-protein diet can cause osteoporosis?

Studies done many years ago suggested that eating a lot of protein increases calcium loss in the urine and therefore it was thought that eating protein weakens bones by taking calcium out of them. However, recent studies show that eating protein increases calcium absorption so the extra calcium in the urine comes from increased absorption, not from being take out of bones. Reports in the American Journal of Clinical Nutrition (Volume 78, Issue 3, 2003) showed that eating plenty of protein and lots of foods from plants helps to keep bones strong. Most scientists now feel that a very low-protein diet can cause osteoporosis, while a moderately high-protein diet may help to prevent it.

Learn how to make healthful eating easy and delicious with
The Good Food Book
It's free -- with 100 recipes.

Saturday, April 08, 2006

Does blood pressure in teens predict future hypertension?

In 1976, 413 high school runners in Finland competed in a 2000-meter race. At the time of the race and in a follow-up study twenty-five years later, the faster runners had much lower blood pressures than the slower ones (International Journal of Sports Medicine, July-August 2005.)

The researchers wanted to know whether a maximal endurance test to measure aerobic fitness in adolescence would predict high blood pressure in adults. This is the first study to show that faster teen age runners have lower blood pressures and that the lower blood pressures persist long after they stop running. In their teens, the faster runners were more fit than the slower runners, and their dedication may have persisted into later life. Or the faster teen-age runners may have had some physiological advantage that kept their blood pressure lower and made them less likely to suffer heart attacks in later life. Perhaps the faster runners were genetically superior to the slower runners, or something in their lifestyles made them faster as teenagers and also caused them to have lower blood pressures throughout their lives. Either way, the findings of this study should encourage early participation in sports and lifelong exercise.

Friday, April 07, 2006

How can I get rid of the fat on my thighs?

If you are woman who is thinking about getting liposuction to rid yourself of the fat in your thighs, think again. Dr. Anne B. Newman, of the University of Pittsburgh found that thigh fat may be good fat (Journal of Clinical Endocrinology & Metabolism, August 12, 2005). Older women with lots of fat in their thighs are at much lower risk for ''metabolic syndrome," a condition associated with high blood sugar, cholesterol and blood pressure that increase risk for diabetes and heart disease. The bad fat appears to be stored in the abdomen and wraps around organs. In post-menopausal women, heavy thighs and buttocks are associated with lower triglycerides, blood sugar and blood pressure. However, women who also stored lots of fat in their bellies lost much of their advantage.

We aren’t sure how thigh fat prevents disease. It may be a receptacle that draws triglycerides and other fats from the bloodstream or it may draw fat from the abdomen and around organs where it could be lethal. Sadly, there is no way to store fat only in the thighs. When you gain weight, you add fat everywhere. But it’s safer to look like a pear than an apple.

When you want to lose fat in a specific place, you need to lose weight overall; there's no such thing as spot reduction.

Thursday, April 06, 2006

Does strength training prevent sports injuries?

Hamstring tears are very common soccer injuries. A study in Scandinavian Journal of Medicine & Science in Sports shows that preseason strength training helps to prevent injuries to these muscles in the back of the upper legs (Volume 13, Issue 4, 2003). Players from two of the best soccer teams in Sweden were divided into two groups. One group received specific hamstring training of 10 weeks of twice a week, using a special device to overload the hamstrings eccentrically. The trained group had less than one third the hamstring injuries of the untrained group, and also had greater improvement in hamstring strength and running speed.

The findings of this study should encourage preseason strength training for other muscle groups stressed in any sports. While stretching can make muscles longer to exert a greater torque on joints, it has not been shown to prevent injuries. Muscles are injured because the force on them is greater than their inherent strength, so they tear. Resistance training makes muscles stronger so that they can withstand greater forces and therefore helps to prevent injuries.

You'll find reports on prevention and treatment of the most common sports injuries in the Fitness section of www.drmirkin.com

Wednesday, April 05, 2006

How can I get rid of the fungus that has made my big toenail thick and yellow?

Fungus infections cause less than five percent of deformed nails. Drying of skin and skin conditions such as psoriasis are more common causes. The part of nails that you see is dead. Living nails are located underneath the skin at their base. It takes four and a half months for the nail to grow from the nail plate to its end where you cut it off. During this time, the nail dries out and the ends can crack and fray. So the most common cause of deformed nails is drying, which is best treated by coating the nails with nail polish to slow water loss.

Most deformed nails are caused by skin conditions such as psoriasis or seborrheic dermatitis. If you have thickened toenails, check with a dermatologist who will clip off a piece of the nail and place it in a special bottle to culture it for a fungus. Since a fungus infection in the nail starts in the plate underneath the skin and no creams can get into the nail plate, pills are the most effective treatment for toenail fungus infections. A special laquer called Penlac can cure some fungus nails when applied for several weeks. Fungus infections can be cured with drugs such as itraconazole or terbinafine, but if no fungus is present, fungus pills will not help. If no fungus is present, most effective treatment is to keep the nails short. Go to a medical supply store and buy surgical quality nail clippers that are strong enough to cut thickened toenails without tearing them.

Tuesday, April 04, 2006

Is potassium deficiency a common problem in athletes?

Not unless they are trying to control weight by vomiting. A few years ago, one of the best female long-distance runners in the country came to me to find a cause for her sudden drop in performance. All tests I ordered were normal except for a low blood level of potassium. The most common cause of potassium deficiency is vomiting, but she repeatedly denied doing this. I then requested that she collect her urine for one day, and the laboratory reported that it contained three times as much potassium as normal. This proved that she was bulimic. To control her weight, she was sticking her finger down her throat and making herself throw up. After she was able to accept the diagnosis, she got help, stopped vomiting and went on to win several long distance running titles.

The kidneys and sweat glands conserve potassium so effectively in response to low body levels that potassium deficiency rarely occurs in healthy athletes. Even with prolonged exercise in very hot weather, potassium needs can be met by eating a normal diet because potassium is found in virtually all foods except refined sugar. On the other hand, potassium deficiency can be caused by drugs, such as diuretics and corticosteroids. It can also be caused by diarrhea or repeated vomiting. With diarrhea, potassium is lost in the stool. With vomiting, potassium is lost in the urine. In both athletes and non- athletes, the most common cause of low potassium blood levels and high potassium urine levels is vomiting.

Monday, April 03, 2006

How can aspirin cause hyponatremia?

Several recent studies show that aspirin, Indocin, Celebrex and other arthritis pain medicines may cause some cases of hyponatremia. These medications, often taken to relieve muscle and joint pain, can cause the body to retain fluid during exercise (Medicine & Science in Sports & Exercise, May 2005).

For more than 40 years, sports medicine experts have told athletes in endurance events to take fluids frequently during events lasting more than one hour. However, on rare occasions, novice athletes have died of hyponatremia in these endurance events. Hyponatremia is caused by drinking too much fluid and is not caused by excessive loss of salt in sweat. The extra fluid expands blood volume and dilutes blood salt levels, which forces fluid to enter and swell the brain, causing nausea and vomiting, weakness, headache, and extreme tiredness. Since these same symptoms can be caused by dehydration alone, the only way to diagnose hyponatremia is with blood tests.

How much fluid should you drink? Experts do not agree because thirst is a late sign of dehydration. The American College of Sports Medicine recommends three to six cups of fluid per hour. 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 two to three cups per hour. Above all, do not take aspirin or any arthritis pain medicines before you compete in events taking more than an hour.

More on hyponatremia

Sunday, April 02, 2006

Should you wear socks with your running shoes?

The main purpose of socks is to keep your feet and shoes from smelling. Foot odor is caused by bacteria or fungi rotting old skin. Your skin turns over every 28 days. A new cell starts on the bottom layer of skin, then another skin cell forms underneath it. The process continues until the bottom cell reaches the top and is sloughed off as dander or dandruff. If you don't wear socks, your old skin deposits in the shoes where it rots and emits an offensive odor. Socks prevent the old skin from getting into your shoes, and washing your socks gets rid of the old skin.

The bacteria that rot your old skin grow luxuriously when the skin is wet. If you have a problem with foot odor, try pouring a small amount of powder into the toes of your socks before you put them on will help to keep your feet dry during the day and prevent bacteria from growing. Avoid wearing the same pair of shoes more often than every other day so they can dry out between use. You can also kill the bacteria by applying a common deodorant containing aluminum chlorohydrate to your feet at bedtime and sleeping with socks on.

Saturday, April 01, 2006

What’s the connection between obesity and diabetes?

A paper in the Journal of Cell Metabolism (March 2005), shows how being overweight can cause diabetes. Being overweight fills your fat cells so they can’t store much more fat. Then the body stores fat in muscles and liver. This causes muscles to produce a chemical called PPAR-Alpha which causes muscles cells to bring in and burn more fat, which prevents muscles from using sugar for energy. So blood sugar levels rise. The fat in muscle cells also blocks insulin receptors from grabbing onto insulin which prevents insulin from driving sugar into cells. This drives blood sugar levels even higher.

Daniel P. Kelly, director of the Center for Cardiovascular Research at the Washington University in St Louis, genetically engineered two different types of mice: one type that made extra PPAR-alpha in their muscles and another that lacked that molecule. They found that mice that overproduce PPAR-alpha become diabetic even though they are thin, because the muscle cells can burn only fat for energy, which prevents muscle cells from using sugar. This causes blood sugar levels to rise very high and the mice to become diabetic. On the other hand, mice who did not make PPAR-alpha grew very fat, but did not develop diabetes. If the scientists could make a drug to block PPAR- alpha, perhaps they could prevent diabetes. This research explains why the majority of people who develop diabetics are also obese.

Are you pre-diabetic? What can you do?