Leucine No Better than Carbs for Energy

A study from Australia showed that leucine helps athletes exercise longer (European Journal of Applied Physiology, August 2006), so now exercisers are lining up to waste their money on supplements that are no more effective than any other source of sugar.

Leucine is a branched chain amino acid that the liver readily converts to sugar. Your body needs extra sugar during endurance exercise, and it doesn't care where it gets it. Your brain gets more than 95 percent of its energy from sugar in your bloodstream. It cannot store extra fuel in its cells. However, there is only enough sugar in your bloodstream to last three minutes. To prevent blood-sugar levels from dropping, your liver constantly releases sugar from its cells into your bloodstream. There is only enough sugar in your liver to last up to 12 hours at rest, and you run out of liver sugar much faster than that when you exercise.

Your liver then makes sugar out of certain protein building blocks called branched chain amino acids in a process called gluconeogenesis. So taking leucine, a branched chain amino acid, helps to maintain blood sugar levels, but so will eating any source of carbohydrates. Athletes buy special concentrated sugar gels, mineral-sugar drinks, and all sorts of expensive exercise foods. None are any more effective in prolonging endurance than ordinary food sources of carbohydrates such as a soda, an orange or banana, a peanut butter and jelly sandwich, a bagel, cookies or whatever you like. More

Belly Fat: Why it's More Dangerous than Hip Fat

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

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

Fat Restriction: Don't Limit the Good Fats

Almost 50,000 women in the Women's Health Initiative Dietary Modification Trial from Harvard Medical School were given dietary counseling to reduce their fat intake to less than 20 percent of their daily calories (Clinical Diabetes, July 2006). This intense dietary counseling did not reduce the incidence of heart attacks, strokes or cancers even though the women reduced their intake of fat by 8.2 percent.

Data from the eight-year follow up show that it is difficult to reduce total fat intake, and that dietary counseling to reduce total fat intake does not reduce the risk of heart attacks or cancers. It lowered weight only an average of three pounds and diastolic blood pressure only slightly. However, other studies have shown that reducing total fat intake does lower risk for certain cancers.

The probable reason for these dismal results is that food contains both good fats and bad fats. Most doctor agree that we should restrict saturated fats found in meat, chicken and whole milk diary products, and partially hydrogenated fats found in many prepared foods. However, the monounsaturated fats found in seeds and nuts and the omega-3 fatty acids found in seafood and seeds are healthful fats that should not be restricted. More

Older Exercisers Recover As Fast As Children

As lifelong exercisers age, they find they can’t hit a tennis ball or golf ball as hard, run as fast, lift as heavy, or perform as well, whatever their sport. A study from Yokohama City University in Japan shows that this gradual decline is caused by loss of muscle strength. However, the most significant finding of the study was that older men can recover from hard workouts as quickly as younger men (Applied Physiology, Nutrition and Metabolism, June 2006). Another encouraging study in the same journal, from the University of Southern California in Los Angeles, shows that men over 60 who exercise regularly are far stronger than their non-exercising counterparts.

A study from Brock University in Canada also shows that older people can recover from hard exercise as fast as young children can (Exercise and Sports Science Reviews, July 2006). The authors feel that previous studies on the subject are flawed. Since children cannot exercise at the same intensity as older people can, they do not put as much stress on their muscles as older people do and therefore do not suffer as much muscle damage. It is the decreased intensity causing less muscle damage that allows children to appear to recover faster from all-out exercise. Children can put only about 60 to 80 percent of the power per weight exerted by adults. They do not work as hard during intense exercise, evidenced by far less lactic acid in their blood streams. Children can do more repeat sets of lifting heavy weights because they do not lift as close to their maximum as adults do. They can do more “attempted all out” wind sprints than adults do because they don’t work as close to their maximum. So the decline in athletic performance with aging is not caused by failure to recover from hard exercise.

If you are an older athlete who competes in sports, you will be able to recover from your hard training days as fast as younger athletes, but you will gradually lose strength, speed and coordination over the years. Every muscle in your body is made of millions of individual fibers. Each fiber is enervated by a single nerve that causes it to contract. With aging, you lose nerve fibers. So with each loss of a nerve fiber, you lose use of the corresponding muscle fiber and, with fewer functioning muscle fibers, you lose strength. Coordination drops also because of the loss of nerve fibers. Since speed depends on strength, you also lose speed. However, if you exercise regularly, you enlarge each of the remaining individual muscle fibers. Even if you have fewer functioning fibers, the larger individual fibers can generate more force to make you stronger. The good news from these studies is that the same training principles apply at any age. Even if you cannot compete effectively against younger people, you are likely to find yourself winning age-group competitions as your peers drop out. If you are not a regular exerciser, it’s never too late to start. How to Start an Exercise Program

Slow Down Gradually After Hard Exercise: Why?

At the end of a marathon, a runner sprints over the finish line, falls down and lies unconscious for a short time. What's the most likely cause? The possibilities include dehydration, hyponatremia (excessive fluid intake with too little salt in the blood), heat stroke, drunkenness, a heart attack or stroke. Usually it is none of these. Almost all athletes who collapse after finishing a marathon suffer from postural hypotension: lack of blood flow to the brain because blood drops from the brain to the legs. Treatment is to lie the person on his back, raise his feet high over his head and wait for him to revive. If he or she is not alert within seconds, you should consider the more serious causes of unconsciousness and get medical help immediately.

When you run, your heart pumps blood through your body, but it gets lots of help from your legs. When your leg muscles contract, they squeeze veins near them to push blood toward your heart. When your leg muscles relax, the veins near them fill with blood. This alternate contracting and relaxing of your leg muscles serves as a second heart. When you sprint toward the finish line, your leg muscles increase their pumping of blood. If you stop suddenly, the leg muscles top pumping and blood pools in your legs, your brain doesn't get enough oxygen, and you pass out.

This is the reason you should always cool down after vigorous exercise. If you slow down gradually, your leg muscles stop pumping gradually and you heart has time to pick up its share of the workload. Many people believe that cooling down helps to prevent muscle soreness by clearing lactic acid from muscles, but there is no evidence to support this theory. Muscle soreness after exercise is caused by small tears in the muscle fibers, not by accumulated lactic acid. Plan to cool down just to prevent dizziness or fainting.

Prevent Memory Loss with Exercise

Dementia with aging is associated with every risk factor for heart attacks: smoking, overweight, lack of exercise, high blood pressure and cholesterol, abdominal obesity, diabetes, kidney damage, eating too much saturated fat, refined carbohydrates and calories, not eating enough vegetables, and so forth. A study from the University of Edinburgh in Scotland shows that if you don't want to lose your mental function with aging, you had better start and stay on a vigorous exercise program (Neurology, October 2006).

Four hundred and sixty survivors of the Scottish Mental Survey of 1932 were tested on the same general memory tests at age 11 and again at age 79. They also were tested at age 79 for their level of physical fitness by having tests for grip strength, 6- meter walk time, and lung function. Those who had the highest scores for physical fitness also had the highest scores for mental function. They also found that those with the highest IQ at age 11 had the best lung functions at age 79, which may mean that intelligent people are more likely to stay in shape. This study adds to the evidence that physical exercise protects your brain. More

Fatigue Causes Poor Coordination

Fatigue reduces both strength and accuracy. There's a physiological reason why tiredness weakens muscles. Muscles are made up of thousands of fibers. Each fiber stores sugar. and when it runs out of its stored sugar, it cannot contract effectively. As you tire, your muscles have fewer fibers to contract and you become weaker and less coordinated. This means that a pitcher who is warmed up and fresh will have more active fibers in his muscles and be able to throw more accurately and faster than when he is tired. A fresh football player can kick further and more accurately than when he is tired. That's why professional and college sports teams have large rosters, so they always have plenty of fresh players.

The same principle applies to boxers, wrestlers, tennis players and so forth, but they do not have the luxury of calling in a substitute. If you compete in an individual sport that requires both endurance and coordination, take it easy early in your competition and save something for the end. For more information on sustaining strength and coordination see my report on Carbs for Endurance

Calories Burned During Exercise: Measure with METS

To help you determine how many calories you use during various activities, scientists recommend a common measure called a MET, the amount of energy you use when you sleep. It comes out to about one kilo-calorie per kilogram of body weight, or one half a calorie per pound. For example, a 130-pound person burns 60 calories per hour during sleep. A 155-pounder uses 70 calories per hour.

When you ride a bicycle at 12 miles per hour, you are exercising at about ten METS or 10 times the amount of energy that you use during sleep. That's the same as running a 10-minute mile, playing racquetball competitively, jumping rope at a moderate pace or playing in a soccer game. To show you how much you increase your metabolism during exercise, consider that 10 METS are equal to five times as much energy as you use when you wash dishes, shop, cook, iron or walk at a leisurely pace. Also see: How Much Exercise to Lose Weight

Mild Dehydration Causes No Harm

The Gatorade Sports Science Institute in Barrington, Illinois published a study showing that 46 percent of recreational exercisers are dehydrated (Applied Physiology, Nutrition and Metabolism, June 2006). However, with good reason, the study does not say that they are harmed. There is no data anywhere to show that this mild dehydration affects health or athletic performance. Another study from the University of Connecticut shows that a person must lose a tremendous amount of fluid before it affects his performance (Medicine & Science in Sports & Exercise, October 2006).

When you exercise for more than an hour, you may need to take fluid, but not too much. Excessive fluid can cause a potentially fatal condition called hyponatremia. Normally, the amount of salt and other minerals in your bloodstream should equal the same total mineral content in every tissue in your body. If the mineral concentrations are not equal, they try to become equal. Fluid moves from the area of lower mineral content to that of the higher concentration. If you take in so much fluid that it lowers the mineral level in your blood, levels in your brain are higher than those in your bloodstream. This causes fluid to move from your bloodstream into your brain, which increases pressure in your brain and can cause seizures and unconsciousness. The swelling can cause permanent brain damage.

Hyponatremia is a disease seen almost exclusively in people who are not exercising near their maximum. The major risk factor is having more time to drink than to concentrate on pushing the pace, no matter what the sport or the duration of the event. Top athletes drink very little fluid during competitions such as bicycle racing, marathon running or cross country skiing, because it is so difficult to drink while you are exercising near your maximum. On the average, a world-classes marathon runner drinks less than a cup an hour during a race. This is far less than the amount recommended by the American College of Sports Medicine just a few years ago. On the basis of our present knowledge, it may not be safe for mediocre athletes to take in more than 800cc per hour (3.5 cups).

Recent studies show that fit humans can tolerate significant fluid loss before their performance suffers, and that most cases of muscle cramps are not caused by dehydration or salt loss. They are caused by muscle damage itself and can be controlled by stopping exercise and stretching the cramped muscle.

Diabetics Can Exercise Before Or After Meals

Exercise helps to prevent blood sugar from rising too high after meals. The only places that your body can store sugar are in blood, liver and muscles. When a diabetic’s muscles are full of sugar, dietary sugar goes from the intestines into the bloodstream, causing high spikes in blood sugar levels. On the other hand, when the muscles are empty, sugars go from the intestines into the bloodstream and then directly into muscles to prevent the spike. Several studies show that it doesn’t make any difference when you empty your muscle cells. Blood sugar spikes are prevented by exercising both before and after meals.

An exciting study from Maastricht University in the Netherlands shows that a single bout of vigorous exercise can help control blood sugar for 24 hours in people whose pancreas make no insulin whatever (Medicine and Science in Sports and Exercise, December 2006). Exercise is a potent treatment for both Type I and Type II diabetics. Any diabetic who does not exercise regularly should check with his or her doctor and get started. See my report on Insulin Resistance

Warm Up to Increase Endurance, Prevent Injuries

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.

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.

Chidren's Exercise: How Much Do They Need?

Children need at least 90 minutes of exercise a day to avoid heart disease when they are older, according to a study reported in Lancet (July 23, 2006). The old guidelines recommending 30 minutes of exercise three times a week, or even an hour a day, do not appear to be adequate for preventing obesity and heart disease. Researchers used heart rate monitors to measure the activity of 1700 nine-to-fifteen-year-olds in Denmark, Estonia, and Portugal. They then calculated a heart-attack risk score consisting of blood pressure, cholesterol, insulin resistance, and skinfold thickness.

They compared physical activity from the heart rate monitors with the heart attack risk-factor score and found that the more active the child, the lower the heart attack risk score. Many of the children who exercised for 60 minutes a day were still overweight and had high heart attack risk scores. The authors suggest that the lack of regular physical activity is likely to mean that the children are spending too much time watching TV, playing video and computer games, and eating junk food. There is no reason to expect that the results would be different with American children. The current recommendation of at least an hour per day of moderate activity in children may not be sufficient for future heart health.

Eight Glasses of Water a Day Not Needed

Do you believe that a person needs to drink eight glasses of water every day? If you do, you will have a lot of extra trips to the bathroom. Why do so many people believe this rule? The number originally came from the National Academy of Sciences of the United States Food and Nutrition Board, which publishes recommended daily allowances of nutrients. The 1945 edition of the Food and Nutrition Board recommended: "A suitable allowance of water for adults is 2.5 liters (about 8 cups) daily in most instances." This amount is based on the calculation of one milliliter of water for each calorie of food. HOWEVER, the Board also noted that most of the water you need is in the food you eat.

All foods contain water. Even the driest nut or seed has a lot of water in it. Furthermore, when food is digested, it is converted to energy, carbon dioxide and WATER. Most people can get the fluid the body needs from food, and they 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 turns the solid food into liquid. If you don't drink enough fluid, your stomach takes fluid from your blood and adds it to the food in the stomach to create the soup. The pyloric valve will not let food pass to the intestines until this liquid soup is formed. Then the liquid 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 and turns your stool into hard rocks, causing constipation.

A study from the Journal of the American College of Nutrition showed that plain water is not needed as long as enough fluid is obtained from other drinks and food. Twenty-seven healthy men consumed one of two diets for three-day periods and were studied in a lab setting. The first diet included plain water while the second omitted it, relying on only foods, orange juice, diet soda, and coffee for fluid. None of the nine measures of hydration were affected.

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, 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 health benefit from forcing yourself to drink eight glasses of water a day.

Diabetes Risk: Lifestyle More Important Than Genes

You may inherit a susceptibility to Type II diabetes, but you do not inherit the disease. Risk factors for developing diabetes include: a family history of diabetes; storing fat primarily in the belly; high triglycerides; low HDL (good) cholesterol; blood sugar higher than 200 thirty minutes after a meal; fasting blood sugar above 110; excess hair on the face or body (in women); or diabetes during pregnancy. A person with any of these warning signs should immediately make lifestyle changes to prevent diabetes: avoid refined carbohydrates (foods made with flour, white rice, milled corn; all added sugars and drinks that contain sugar), exercise regularly, lose weight if you are overweight, and keep your weight controlled for the rest of your life. If you do this you will be at low risk for developing diabetes, even if you have genes that make you susceptible.

Studies from the Journal of the American Medical Association show that one of three Americans will become diabetic, with women more likely to develop diabetes than men. The average person who is diagnosed with diabetes at age 40 will die 11.6 year earlier than a non-diabetic and he or she will be severely incapacitated with one or more side effects of diabetes 18.6 years before a non-diabetic. Early lifestyle changes can add years to your life.

Lifting Weights Helps to Prevent Diabetes

One third of Americans will become diabetic because they eat too much and exercise too little. A study in Medicine and Science in Sports and Exercise (July 2006) shows that lifting weights can help to prevent and to treat diabetes.

Extra fat prevents your body from responding normally to insulin. Before insulin can do its job of driving sugar from the bloodstream into cells, it must first attach to little hooks on cell membranes called insulin receptors. Having extra fat in cells turns these receptors inward, making it far more difficult for insulin to attach to the receptors. This prevents insulin from doing its job of lowering blood sugar levels, even though your body is making plenty of insulin. That’s why anything that makes you fat increases your risk for diabetes. Doctors can measure how cells respond to insulin with a sugar tolerance test.

In this study, adolescent boys were given a program of lifting heavy weights twice a week. After only 16 weeks, their muscles were larger and they lost fat. Sugar tolerance tests showed that the ability of their bodies to clear a load of sugar from their blood streams improved dramatically. This means that a regular weight lifting program decreases insulin resistance and thus reduces risk for becoming diabetic.

How Much Exercise for Weight Loss?

How much do you need to exercise to lose weight? In one recent study, researchers asked people to walk and count an extra 2000 steps each day (Journal of Human Nutrition & Dietetics, August 2006). This is really a minimal amount of exercise. They also kept complete food diaries. They lost weight and did not increase their food intake. When you start an exercise program, your appetite may increase, but this will not increase your caloric intake to equal the extra calories that you burn. For example, if you burn 600 calories with added exercise, you may take in 200 calories extra and you will lose weight.

Exercise helps you lose weight by raising your metabolism so you burn more calories for several hours after you finish exercising. However, only vigorous exercise that increases body temperature and makes you sweat will increase your metabolism enough to continue burning more calories after you finish. Overweight is a major cause of premature death and increases risk for heart attacks, strokes, cancers and arthritis. If you are out of shape and want to lose weight, get a stress cardiogram and ask your doctor to clear you for an exercise program. Start slowly and then gradually increase the intensity of your exercise over several months.

Why Blood Pressure Rises with Age

Blood pressure often rises with aging. Contrary to what many doctors think, salt, obesity and alcohol have little to do with this rise.

High blood pressure is associated with heart attacks, strokes, aging and death. Recent research shows that high blood pressure associated with aging is probably caused by damage to the arteries leading to the kidneys. Obesity, excess salt and alcohol cause reversible high blood pressure. Taking a large amount of salt can cause your body to retain fluid, enlarge blood volume and raise blood pressure temporarily, but blood pressure returns to normal soon afterwards. For most people, taking in a lot of salt does not raise blood pressure. Drinking alcohol raises blood pressure only for a short time. Obesity is associated with a sustained high blood pressure at any age, and is usually reversible with weight loss.

Several studies show that damaged kidney arteries, called intimal fibroplasia, are the most likely cause of high blood pressure and that prevention of high blood pressure with aging includes preventing kidney arterial damage by eating plenty of fruits, vegetables, whole grains, beans and nuts, reducing your intake of processed foods and dairy products, exercising and avoiding overweight. More on the diet that lowers blood pressure

Detecting Performance-Enhancing Drugs

World records in sports are broken by better athletes, better training methods, better nutrition or new drugs. Drugs appear to be the cause of many recent records in sports requiring strength and speed. Many bicycle racers know that some drugs that make them better riders can’t be detected by testing techniques that are available today. A recent study shows that laboratories have no definitive test to discover athletes who take erythropoietin (EPO), a drug to boost their red blood cell counts (Haematologica, August, 2006). Athletes have found that taking very low doses of EPO daily will raise red blood cell counts, and will not give test results high enough to show that they are taking extra EPO.

The primary limiting factor to how fast a person can ride a bicycle over long distances is the time it takes to move oxygen from the lungs into the muscles. So anything that increases oxygen transport from the lungs into the bloodstream, or carries more oxygen in the bloodstream, or moves oxygen faster from the blood into muscles will make a person a faster bicycle racer. Since more than 95 percent of the oxygen in the bloodstream is carried by hemoglobin in red blood cells, anything that increases the concentration of red blood cells will help a racer ride faster.

When healthy people do not get enough oxygen, their kidneys produce a hormone called EPO that causes the bone marrow to make more red blood cells. When athletes are given additional EPO, their red blood cell counts rise and their performance improves.

Doctors can do blood tests for EPO, but the hormone lasts only a few days in the bloodstream, so athletes who stop taking EPO several days before testing may not be caught. Some athletes tried to foil the test by adding pepsin, a chemical found in spot removers, to their urine samples. However this destroyed all of the EPO including their own natural EPO, so they failed the test because a person is supposed to have some EPO. The new study shows that athletes have now found a way to circumvent the test by taking very low doses of EPO every day.

Carbohydrates Can Increase Endurance

A study from The University of Bern in Switzerland shows that a high carbohydrate, high-fat diet for three days before competition can help athletes store more fat in their muscles and use much more muscle fat for energy during exercise (European Journal of Applied Physiology, November, 2006). Endurance-trained athletes exercised for three hours to empty sugar and fat reserves from their muscles. Then they ate a high-carbohydrate, low-fat diet for 2.5 days or the same diet with lots of added fat for the last 1.5 days. Athletes who ate the high-carbohydrate, high-fat diet stored 55 percent more fat in their muscles and used more than three times as much of that fat during exercise.

The data on fat storage may have no practical value for endurance athletes because the authors were not able to show that the extra fat stored in muscles increased endurance. This is probably because there is almost an unlimited amount of energy available from a person’s own body fat. Changing the percentage of fat use from body fat to muscle fat would not increase energy sources and therefore would not increase endurance.

Carbohydrates are another story. Normally there is only a small amount of carbohydrates stored in the muscles, liver and bloodstream. Storing extra carbohydrates in muscles is beneficial because when a person runs out of stored muscle sugar, his muscles hurt and are more difficult to control. In the 1940s, Per Olaf Ostrand showed that a high carbohydrate diet for several days before athletic competitions helps a person store more sugar in muscles, which does increase endurance. Since then athletes have eaten high-carbohydrate diets before competition and often have pre-race pasta parties. Subsequent studies showed that highly-conditioned endurance-trained athletes can maximally fill their muscles with sugar just by eating their usual meals and cutting back on their heavy workloads for a few days before competition.