Wednesday, August 31, 2005

Does exercise build strong bones?

If a woman lives long enough, she can expect to have osteoporosis. Lifting weights during adolescence can help prevent osteoporosis when women are older. A woman’s bones are strongest when she is 20, and after that, she loses bone continuously for the rest of her life. If an elderly woman breaks her hip from osteoporosis, she has a 20 percent chance of dying from complications within the year. The stronger and larger a woman’s bones are when she is younger, the stronger they will be when she is older.

A muscle can only be as strong as the bones on which it attaches. Lifting weights when a woman is young enlarges her bones and makes them stronger. Just exercising will not strengthen bones. Female marathon runners who stop menstruating because they do not eat enough food to meet their calorie requirements can develop osteoporosis even if they run more than 100 miles per week. To help build bone, exercise must be done against resistance. All women can gain bone by lifting weights at any age.

Are colon cleansers necessary for good health?

No! Regular use of colon cleansers or laxatives can harm you by blocking the absorption of nutrients from your colon into your bloodstream. There are two absorption systems in the digestive tract. First the food that you eat passes from your stomach to your upper intestines, where secretions from your stomach, liver, intestines and pancreas break down carbohydrates, fats and proteins into their building blocks. Only these building blocks -- basic sugars, amino acids, fatty acids and glycerol -- are absorbed from your intestines into your bloodstream. The food that is not broken down cannot be absorbed so it passes to your colon.

Bacteria in your colon convert undigested starches into short chain fatty acids that heal ulcers, prevent colon cancer and other cancers, reduce the pain of arthritis, prevent the arterial damage of arteriosclerosis, lower cholesterol, and even lower high blood pressure. Colon cleansers or laxatives reduce the absorption of these beneficial short chain fatty acids. Promoters who recommend these products claim that they remove old stool that gets stuck and rots in your colon, but this is ridiculous. Undigested waste products stick together by a physical process called surface tension, so they cannot pass by older stool. If you are often constipated, see report #G211.

Are "Slow Lifting" programs effective?

The technique called super-slow weight lifting can help older people become very strong. When you move very slowly with a weight, your muscles fatigue and weaken so that the weight feels much heavier than it is. Moving a weight very slowly in sets of ten causes the same amount of damage as moving a much heavier weight rapidly, and causes the same type of muscle damage. Lifting lighter weights slowly is far less likely to cause injuries than heavy lifting. You can become just as strong using the slow lifting technique, and you are more likely to stay injury-free.

However, if you are training for a sport that requires fast movements, the super-slow training method may not be your best choice. Training is specific. You have to exercise against resistance moving fast to be able to use your muscles quickly. Slow lifting can make you strong, but it is not the best way to prepare you for fast-moving competitive sports such as tennis, ping-pong, cycling, basketball or volleyball. report #8845 gives more strength training tips.

Tuesday, August 30, 2005

Do "grow taller" supplements really work?

These ads are so unbelievable that the people who wrote them must be laughing as they steal people's money for their totally worthless products. They tell you that if you take their pills or wear their insoles, you can continue to grow until you are as tall as you like, at any age. If that were true, we would see people who are 15 feet tall and basketball would be an entirely different sport.

They want you to believe that when you eat their special blend of kudzu vine and other rampant-growing plants, you will grow like the vines. Of course this is ridiculous. Kudzu vine grows rapidly because of its genetic structure called DNA, but you cannot absorb DNA from plants or animals that you eat; it is broken down in your stomach and intestines into amino acids, the building blocks of protein.

Or they tell you that their product will stimulate your growth hormones, but even if that were true, once you have gone through puberty, no amount of growth hormone will lengthen your bones. See report #8551 for more about the so-called growth hormone releasers.

Bones do not grow throughout their length. They grow from growth centers, called the epiphysis, near their ends. When a person reaches puberty, growth centers close one after the other until all the growth centers are closed forever and a person's bones can never grow again. After that, a person can grow wider, but not taller. The tragedy is that some people will shell out their hard earned money to someone who is making fun of them. They offer a money-back guarantee, but they know you will probably be too embarrassed to ask for your money back, and many people report that their money is never returned when they request it from these scams.

What's the best treatment for elbow pain?

If you have pain on the tendons attaching at your elbow, you may have tennis elbow, damage to these tendons. Place your hand and arm on the table with your palm facing up. If your elbow hurts when you try to raise your fist by bending you wrist, you probably have forehand tennis elbow. If the same maneuver hurts when your palm is down, you probably have backhand tennis elbow.

The odds are overwhelming that your orthopedist will try to inject cortisone-type drugs into that tendon, and you may feel better for a few weeks. However, at six months, it won't make any difference whether you received the injection or not. Cortisone gives you only short term freedom from pain. Treatment is to strengthen the tendon by lifting very light and then progressively heavier weights.

For more on treatment of sports injuries see the Fitness section of

Can high blood pressure be avoided with exercise?

The current guidelines state that high blood pressure is any value over 120 when the heart contracts and over 80 when it relaxes. Ninety-one percent of Americans will suffer from high blood pressure, which causes heart attacks, strokes, and kidney damage. To reduce this frighteningly high incidence of this silent killer, The American College of Sports Medicine recommends that every able person start an exercise program (Medicine and Science in Sports and Exercise, November, 2004). Certain conditions may temporarily preclude exercising, so check with your doctor.

Anything that expands blood volume will raise blood pressure. Diuretics lower blood volume and are therefore the most effective medication for lowering high blood pressure. However, diuretics tire you earlier during exercise because dehydration is a major cause of fatigue. Vigorous, prolonged exercise also dehydrates you and can lower blood pressure for 24 hours or more after you stop exercising.

Full fat cells raise blood pressure. When your heart contracts, it pushes a huge amount of blood into your main artery called the aorta. The aorta is supposed to widen and accept the surge of blood that comes with each beat. If the aorta is stiff, it does not expand adequately and blood pressure rises too high. When you are overweight, full fat cells release inflammatory hormones that stiffen the aorta and raise blood pressure. Exercise is a vital part of any successful program to lose weight and keep it off.

If you have high blood pressure, your doctor will probably recommend medication. However, more than 80 percent of hypertensives can have their blood pressure controlled just with diet and exercise. To see if you fall in this group, try my SHOW ME! Diet for two weeks For more on controlling blood pressure with diet see report #8614 and other reports in the Heart Health section of

Why are some men so much more aggressive than others?

A partial answer may come from a study in Biological Psychology (March 2005), showing that the ratio of a man's second finger to his fourth finger appears to predict aggression. The amount of testosterone a baby is exposed to in his mother’s uterus determines how long his fourth finger grows. So men who have been exposed to high levels of testosterone in utero have a larger ratio of the fourth (“ring”) finger to the second (“index”) finger and therefore are more prone to physical aggression later in life. The author of this study states: “This study shows that events in the womb have subtle effects on children's personality." Previous studies have shown that men with higher ratios of the fourth to second finger may be better in sports and are usually more dominant and masculine. On the other hand, these men are at higher risk for autism and immune deficiency. Men have larger finger ratios than women. The authors cautioned that these findings link a larger finger ratio to "a tendency toward physical aggression". They do not show that all men with larger ratios are more aggressive.

Does everyone need to drink eight glasses of water a day?

Drinking lots of water just means you will spend a lot of time running to the bathroom. All foods contain water, and all food is converted to energy, carbon dioxide and water. You can get most of the fluid the body needs from food, and you only need to drink enough water to prevent constipation.

When you eat, the pyloric valve at the end of your stomach closes to keep food in the stomach. Then the stomach takes fluid that you drink and food that you eat and mixes them into a soup. Then the soup passes to the intestines and remains a soup until it reaches your colon. Only then is the fluid absorbed to turn the soup into solid waste in the colon. If you do not have enough fluid in your body, your body extracts extra fluid from your stool, which makes it hard and can cause constipation.

A reasonable amount for a healthy human is one cup of water or any other fluid with each meal. If you have a problem with constipation you may not be drinking enough water (see my report on constipation), but if you are not constipated, you are getting plenty. You'll also want to replace fluids whenever you sweat a lot, particularly when you exercise or in hot weather. Drink water whenever you feel thirsty, but there's no benefit from forcing yourself to drink eight glasses of water a day.

How can I strengthen my heart?

Fitness refers to your heart muscle. The stronger your heart, the more fit you are. The only stimulus that makes any muscle stronger is to exercise that muscle against increasing resistance. To make your skeletal muscles stronger, you have to lift heavier weights or press against greater resistance in any weight-bearing exercise. The only way that you can strengthen your heart muscle is to exercise against greater resistance also.

When you use your legs, your leg muscles squeeze blood from the veins near them toward your heart. Then, when your leg muscles relax, the veins near them fill with blood. This alternate contraction and relaxation of your leg muscles acts as a second heart pushing huge amounts of blood towards your heart. To pump the extra blood from your legs to your heart and then to your body, your heart muscle has to squeeze harder and faster. The harder you exercise, the more blood is pumped by your legs to your heart, and in turn, the harder your heart has to work to push it out towards your body, so your heart has to beat faster and with more force to do more work.

Fitness is determined more by how hard you exercise than by how long you exercise. Exercising at a casual pace does not do much to strengthen either your heart or your skeletal muscles. When you work harder, more blood returns to your heart, and this increased amount of blood fills the inside of your heart and stretches it, so your heart has to pump against greater resistance and the heart muscle becomes stronger.

See report #1049 in the Fitness section of for more on increasing your level of fitness.

Monday, August 29, 2005

Do you want your child to be a champion athlete?

Champion athletes are born AND made.

Lance Armstrong is arguably the greatest endurance athlete of all time. Edward F. Coyle, professor at the University of Texas, has tested him in his laboratory several times over the years. (Journal of Applied Physiology, March 17, 2005). We can be certain that Lance has extraordinary genetic attributes. A laboratory measure of a person’s genetic ability to compete successfully in endurance events is called the VO2max, the maximum amount of blood the heart can pump in a given time span. Lance’s value was 6 liter/min (expressed per body weight as 75-85 ml/kg/min). Of the hundreds of athletes he has tested, Coyle has found only two other athletes in that range. To have great endurance, (and a high VO2max) you have to have a large heart that has to be able to pump huge amounts of blood with each beat. You also have to have a dense collection of blood vessels to deliver oxygen to the muscles and the types of muscle fibers that can generate, power efficiently and resist fatigue.

This doesn’t mean that training is not important. An athletic, lean 20 year old usually has a maximum oxygen uptake of around 40-50. If he stops exercising, it may drop to 30. If Lance becomes a couch potato, his VO2max would drop, but only to about 65. That means that he would still be able to beat most bicycle racers, even when he stops training.

Now we know that if you want your child to grow up to be a champion athlete, he or she must have the right genes, choose the right sport and train very hard in that sport from an early age. With few exceptions, the time of multiple-sport athletes is gone. Champion gymnasts, runners, swimmers, and power athletes usually start training before age 10 and specialize in their chosen sport 12 months a year. Before you expose your child to such intense specialization that it limits his other interests, it is reasonable for you to see how he compares to other children at the same age and experience. A test of VO2max may help you decide if your child is spending his energies in the right place; if the base VO2max is less than 40, he has little chance of being a world-class athlete in an endurance sport.

For more on training before puberty see report #2052 at

Is it better to eat 1-2 large meals or many small ones?

Your body temperature rises for about an hour after you eat. Eating frequently raises your body temperature for longer periods of time, causing you to burn more calories and store less as fat. Several studies show that nibblers are thinner than gorgers. Animals that nibble throughout the day have lower cholesterol levels and less body fat than those that eat all their calories in one meal.

You can shorten your life by drinking a cup of coffee for breakfast, having a small snack at lunchtime and then eating a huge meal in the evening. One study of adult diabetics showed that those who skipped meals were far more likely to be fat. Frequent small meals can help diabetics to lose weight and control their blood sugar levels. The more a diabetic eats at a meal, the higher the blood sugar rises. The diabetics who ate small meals frequently had lower blood sugar levels and produced less insulin throughout the day.

To prevent diabetes see report #1555 at

How can I get the most out of my daily walks?

To become fit you need to exercise vigorously enough to increase your heart rate by at least 20 beats a minute. Walking slowly doesn’t do much to make you fit. There are two ways to walk faster: take longer steps or move your feet faster. To lengthen your stride, twist your hips from side to side and reach forward with your feet. Pointing your feet forward after your heel strikes the ground helps you gain a few inches.

It’s easier for most people to increase their speed than to lengthen their stride. If you move your arms faster, your feet will move faster also. Every time one leg moves forward, the arm on the same side moves back and the arm on the other side moves forward. For every step forward, there is an equal number of arm movements forward. It takes more time for your arms to swing further with straight elbows, so keep your elbows bent.

For more exercise tips see the Fitness section of

Sunday, August 28, 2005

Hyponatremia: too much water

HYPONATREMIA should never happen to you.

For the last 40 years, sports medicine experts have told athletes in endurance events that they should take fluids frequently during events lasting more than one hour. However, three years ago, a 28-year-old woman collapsed and died after finishing the Boston Marathon. Her blood salt levels were extremely low and she died from a condition called hyponatremia. A few weeks ago, a policeman training for bicycle duty died of the same condition. On July 26, 2005, sports medicine experts issued a warning to all athletes from the First International Exercise-Associated Hyponatremia Consensus Development Conference (Clinical Journal of Sport Medicine, July/August 2005).

I have never seen this syndrome in well-conditioned athletes. It has been reported almost exclusively in very thin, less-fit, slower and novice athletes, and is far more common in women. This condition is caused by drinking too much fluid and is not caused by excessive loss of salt in sweat or by exercising. When people with psychiatric problems force themselves to drink huge amounts of water while sitting still, they also can die of hyponatremia, only in this case, it is called water intoxication.

The extra fluid expands blood volume and dilutes blood salt levels. This causes blood salt levels to be very low, while brain salt levels remain normal. Fluid moves from an area of low salt concentration into areas with high salt levels. So fluid moves from the bloodstream into the brain, causing brain swelling. Since the brain is enclosed in the skull, which is a tight box, the brain expands and has nowhere to go, so it is squashed to cause headache, nausea, and blurred vision. Since these are the same symptoms caused by pure dehydration with normal blood salt levels, the only way to diagnose the condition is with blood tests. As blood salt levels drop even lower, the person becomes confused, develops seizures and falls unconscious. You should suspect hyponatremia when the event takes more than four hours, the athlete is a thin woman in her first ultra-long endurance event, and when she has been drinking heavily as she exercises. All people who are confused, pass out or have seizures should be sent to a hospital immediately. The condition requires skilled management because the first impulse of an inexperienced physician is to give intravenous fluids, which dilute blood salt levels further and swell the brain and can kill the patient.

How much fluid should you drink? You will not become thirsty during exercise until you have lost between two and four pints of fluid, so you can't wait for thirst to encourage you to drink. Dehydration makes you tired and it is unlikely that you can replace the lost fluid during a race after you have become thirsty. Blood has a much higher concentration of salt than sweat, so when you sweat, you lose far more water than salt. This causes blood salt levels to rise. Thirst is controlled by certain cells in your brain called osmoreceptors which are stimulated to make you thirsty only after blood salt levels have risen considerably. So you will not become thirsty until you are significantly dehydrated.

The American College of Sports Medicine recommends a limit of 1200cc (5 cups, 2.5 pints, a little over 1 quart, or 2 average size water bottles) per hour, but for a person who is not exercising near his or her maximum, this could be too much. A person exercising near his capacity and not slowed down by fatigue probably does not have to worry about limiting fluid intake. He is working so hard at maintaining intensity, he doesn't have enough time to drink too much. On the other hand, people slowed down by fatigue or those out of shape, should limit fluid intake, probably to less than two large water bottles per hour. If you are exercising for more than an hour, you should also replace salt, either with salted sports drinks or salted foods.

For more helpful exercise and training tips, see the Fitness section of

Why does milk go bad after a few days?

Bacteria grow rapidly in milk, using the sugar, lactose, as their food; chilling slows the growth but does not stop it. Most of the bacteria are beneficial for humans or benign, but some are toxic. As the sugar is consumed the milk becomes sour but is still edible (as in yogurt), and will give a "buttermilk pancake" flavor if you cook with it. However, it does not stay at that stage for long. Soon all of the lactose is consumed so the food value is gone, and the toxic bacteria have multiplied to the point where they are dangerous for human consumption.

For more interesting food facts and healthful eating tips, see the Nutrition section of

Can a child with asthma participate in competitive sports?

All asthmatics can cough and become short of breath when they exercise, more commonly when they run than when they swim. Asthma is triggered by breathing dry, cold air, and swimming usually does not cause asthma because of the moist air above the water. Many children cough, wheeze and become short of breath 5 to 12 minutes after they start to exercise. They usually have exercise-induced asthma and they should be encouraged to exercise. Most can compete in sports, provided that they know how to prevent attacks. Special drugs called beta agonists such as terbutaline, albuterol or salbutamol relieve wheezing, but they give athletes an unfair advantage by helping their muscles to recover faster from workouts so they can do more work.

The International Olympic Committee allows athletes to take these drugs by inhalation only if their physician writes to the Olympic Committee, certifying that they are asthmatics. If beta agonist inhalers do not prevent exercise-induced asthma, you can try a cortisone-type inhaler for several days before competition. Asthmatic athletes can also prevent asthma by warming up very hard 45 minutes before competition and bringing on an attack of asthma. That will often prevent them from getting a second attack when they compete. Research shows that exercise on both land and water helps to control the severity of asthmatic attacks, even in asthmatics who do not compete.

For information on late-onset asthma, see my report #G107

Friday, August 26, 2005

What’s the best way to treat a pulled muscle?

Muscle pulls are a hazard of exercising. The immediate treatment is RICE: Rest, Ice, Compression and Elevation. Stop exercising immediately, apply an ice bag wrapped in a towel on the injured part, wrap a bandage loosely over the ice bag, and raise the injured part above the heart. Remove the ice after 15 minutes and reapply it once an hour for the first few hours. After a few days of rest, you can start a program of massage and stretching.

The only drugs that have been shown to help heal muscles are anabolic steroids or beta agonist asthma medications such as clenbutarol or albuterol. Anabolic steroids can have dangerous side effects and are illegal. Clenbutarol and albuterol appear to be safe in the low doses that are required to hasten muscle healing, but have not been approved by the FDA for this purpose in the United States. You can take pain medicines such as ibuprofen, but they do not speed healing. They may make matters worse if you mask the pain that warns you not to use the injured muscle. Cortisone-type injections block pain and reduce swelling, but they may actually delay healing. The most effective treatment is rest. You should not exercise that part of your body until you can do it without feeling pain. When you return to the activity that caused the injury, start out at reduced intensity and duration, then gradually work back up to your normal program. Stop immediately if you feel pain.

If you have chronic pain in several joints or muscle groups, see reports #J106 and #G115.

More Sports Injuries Reports

Does blood pressure vary at different times of the day?

Yes. You raise your blood pressure in the morning just by being active instead of lying in bed. Blood pressure is the force of your heart contracting times the resistance in your arteries. It stands to reason, then, that being active causes your heart to contract with more force and therefore raises your blood pressure. So if you have high blood pressure and take your blood pressure frequently to follow the effects of your diet and exercise program or any drugs to lower it, be sure to take your blood pressure when you first awake, and before you are active, because any activity raises blood pressure. But don’t use this information as an excuse to stay in bed; inactivity weakens your heart muscle and increases your risk for a heart attack.

More Heart Health Reports

What Causes Muscle Soreness?

Your muscles should feel sore on some of the days after you exercise. If you go out and jog the same two miles at the same pace, day after day, you will never become faster, stronger or have greater endurance. If you stop lifting weights when your muscles just start to burn, you won’t feel sore on the next day and you will not become stronger. All improvement in any muscle function comes from stressing and recovering. On one day, you go out and exercise hard enough to make your muscles burn during exercise. The burning is a sign that you are damaging your muscles. On the next day, your muscles feel sore because they are damaged and need time to recover. Scientists call this DOMS, delayed onset muscle soreness.

It takes at least eight hours to feel this type of soreness. You finish a workout and feel great; then you get up the next morning and your exercised muscles feel sore. We used to think that next-day muscle soreness was caused by a buildup of lactic acid in muscles, but now we know that lactic acid has nothing to do with it. Next-day muscle soreness is caused by damage to the muscle fibers themselves. Muscle biopsies taken on the day after hard exercise show bleeding and disruption of the z-band filaments that hold muscle fibers together as they slide over each other during a contraction.

Nobody really knows how these hard bouts make muscles stronger, but the most likely theory depends on the fact that hard exercise damages muscle fibers. Then other cells release chemicals called cytokines that cause inflammation characterized by soreness (pain), increased blood flow to the injured fibers (redness), and increased flow of fluid into the damaged area (swelling). The damaged muscle cells release tissue growth factors to heal the damaged muscle fibers, and if the athlete allows the muscle soreness to disappear before exercising intensely again, muscle fibers become larger and increase in number by splitting to form new fibers. If the athlete does not wait until the soreness goes away before exercising intensely again, the fibers can be torn, the athlete becomes injured, and the muscles weaken.

Next-day muscle soreness should be used as a guide to training, whatever your sport. On one day, go out and exercise right up to the burn, back off when your muscles really start to burn, then pick up the pace again and exercise to the burn. Do this exercise-to-the-burn and recover until your muscles start to feel stiff, and then stop the workout. Depending on how sore your muscles feel, take the next day off or go at a very slow pace. Do not attempt another intense workout until the soreness has gone away completely. Most competitive athletes exercise at low intensity during recovery, rather than taking days off; this makes their muscles more fibrous and resistant to injury. If you’re not interested in competing, you can take one or more days off until your muscles feel fresh again.

More Fitness Reports

Friday, August 19, 2005

Fitness & Health with Dr. Gabe Mirkin: List of topics and questions

August 28, 2005
What Causes Muscle Soreness?
Does blood pressure vary at different times of the day?
Dear Dr. Mirkin: What’s the best way to treat a pulled muscle?
Reports: Hypoglycemia, DASH diet, Exercise for arthritis

August 21, 2005
Hyponatremia Should Never Happen to You
How does milk turn sour?
Can a child with asthma compete in sports?
Reports: Bleeding gums, MAP, Sudden greying of the hair

August 14, 2005
Champion Athletes Are Born AND Made
How can I get the most out of my daily walks?
Is it better to eat one or two large meals or many small ones?
Reports: Excessive sweating; Dizziness; Mycoplasma

August 7, 2005
How to Strengthen Your Heart
Does everyone need to drink eight glasses of water a day?
Why are some men so much more aggressive than others?
Reports: Leg cramps; Polycystic ovary syndrome; Fungus toenails

July 31, 2005
High Blood Pressure and Lifestyle
What's the best treatment for elbow pain?
Do supplements that are supposed to make you grow taller work?

July 24, 2005
Slow Lifting
Are colon cleansers necessary for good health?
Will a teen's exercise help her bones stay strong when she’s sixty?

July 17, 2005
How Lack of Exercise Shortens Lives
Why do some people develop allergies while others don't?
I’ve heard that cooking destroys nutrients. Would it be better to eat only raw foods?

July 10, 2005
Arches and Running Injuries
More on High Fructose Corn Syrup
Why are bicycle helmets so important?
Will riding a stationary bicycle for 30 minutes every day be enough to make me fit?

July 3, 2005
Should You Restrict Salt?
Is rope jumping a good exercise for fitness?
How can I keep from losing brain power as I get older?
Reports: Glucosamine; Pre-Diabetes; Recovery after workout

June 26, 2005
You Should Never Get Heat Stroke
What's normal for muscle soreness after a workout?
Are barbequed foods dangerous?
Reports: Total body scans; Inflammation; Facial hair

June 19, 2005
Hit a Punching Bag for Fitness
Is it true that iceberg lettuce is completely devoid of nutrition?
I'm exhausted after ten minutes of aerobic dancing; is there any point in continuing with the class?
Reports: Prostatitis; Eye exercises; Restless legs

June 12, 2005
How Does Fatigue Affect Your Strength?
Are monoglycerides and diglycerides the same as trans fats?
I'm too skinny; how can I gain weight?
Reports: fluoride, warts, radon

June 5, 2005
Why Weight Lifters Need Endurance
What could cause constant itching?
Is homocysteine a cause of heart attacks in women?
Are whole grains too high in calories?
Reports: Growth hormone for short children, jellyfish stings, irritable bowel syndrome

May 29, 2005
Who Wins Bodybuilding Contests?
Is it possible to get too much iron in supplements?
How can I get rid of cellulite on my thighs?
Reports: kleptomania, tonsils, booze blockers

May 15, 2005
Anabolic Steroids Make You Stronger, but At What Cost?
How should I use the incline feature on my treadmill?
How can I tell if I am getting enough vitamin D?
What are the best types of beans?