Friday, January 28, 2011

Muscle Sugar: Train Low and Compete High

Muscles use carbohydrates, fats and proteins for energy. You can improve both endurance and speed in athletic competitions lasting more than a couple hours by training your muscles to burn more sugar and less protein and fat during competition.

The most efficient fuel for muscles during exercise is carbohydrates (sugar). The limiting factor for how fast you can move is the time it takes to move oxygen into muscles. Since sugar requires less oxygen than protein or fat, you move faster when your muscles burn primarily sugar. How far you can run, cycle, ski, or skate depends on how much sugar you can store in your muscles before you start exercising and how long you can keep the extra sugar there. When muscles run out of their stored sugar, muscles hurt and you feel tired.

Advantages of Training on Depleted Glycogen
You can teach your muscles to burn more sugar and less fat by starting some of your workouts with muscles that are low in their stored sugar, called glycogen. This forces muscles to burn a higher percentage of fat. However, muscles move faster when they use sugar for fuel, so they try to burn more sugar. They increase the concentration of the many enzymes that help to convert sugar to energy. This allows muscles to burn a higher percentage of sugar during competition so athletes can go faster and improve their chances of winning.

Ways to Deplete Muscle Glycogen
You can start your workouts with low muscle glycogen by: *training after skipping breakfast; *training twice a day, so your muscles have low stored sugar during your second workout of the day; *restricting carbohydrates in your diet during training; *taking prolonged workouts that empty your muscles of stored sugar, or *withholding carbohydrates after a hard workout. The key is to train with low amounts of stored muscle sugar and race with muscles full of stored sugar (Exercise and Sports Science Reviews, October 2010).

How to Increase Sugar-burning Enzymes in Muscles
You can't start all your training workouts with low muscle sugar because it will slow you down, reduce the amount of miles you can do in training, and increase your chances of injuring yourself.

Knowledgeable athletes train by stressing and recovering. They take a hard workout on one day, feel sore on the next, and then take easier workouts until the soreness disappears. They do very intense workouts up to three times a week, rarely on consecutive days. These intense workouts should be taken with muscles full of sugar, so you should eat before your intense workouts and even take sugar during the workout.

However, on your four recovery days, try starting your workouts without eating breakfast. If you feel excess fatigue, your muscles hurt or you have little energy, shorten your workouts and immediately eat extra carbohydrates such as fruits, vegetables, whole grains, beans, and even whole grain bread or pasta.

If you find that you are fatigued too often and take too long to recover from workouts, abandon this training technique. It is not for you. You probably have to take in a lot of sugar during training just to keep up the intensity and volume of work that is required to be a competitive athlete.

What to Do Before Competition

Hundreds of research papers show that you can increase endurance and intensity in competition by filling your muscles with sugar before you compete and then taking sugar during competition. Athletes in endurance events should cut back on their training three days before major competitions and eat extra carbohydrates. This fills their muscles with extra sugar. They should eat a high-carbohydrate breakfast and take sugar during the competition to keep up a regular sugar supply for their muscles.

Thursday, January 13, 2011

Osteoporosis in Men

All men and many women with osteoporosis need to be evaluated to find the cause. More than 75 percent of men with osteoporosis have a serious cause (Osteoporosis International, published online October 9, 2010). Common causes include *low levels of the male hormone, testosterone, *vitamin D deficiency, *excessive loss of calcium through the urine, *an overactive thyroid, *being given too much thyroid hormone, *an overactive parathyroid gland, *smoking, *drinking too much alcohol, *not getting enough exercise, or *taking certain drugs, such as cortisones, that weaken bones.

All people with weak bones should get the following tests: 25-hydroxyvitamin D, testosterone, luteinizing hormone, follicle-stimulating hormone, thyroid-stimulating hormone, parathyroid hormone, and spot urinary calcium-to-creatinine ratio, calcium, phosphorus, and creatinine. If that doesn't tell you why your bones are weakened, you may need to be checked for inability to absorb calcium from your intestines (celiac panel), bone disease (such as multiple myeloma), or taking glucocorticoids, which are often prescribed to transplant patients and those with autoimmune diseases.

Wednesday, January 12, 2011

Fish - Yes; Fried Fish - No

Eating oily fish, like salmon, herring or mackerel, twice a week helps to prevent heart attacks and strokes. Eating oily fish more often than twice a week has not been shown to be any more protective. On the other hand, eating fried fish may increase risk of stroke (Neurology, published online December 22, 2010).

The most popular fried fish are frozen fish sticks, fast-food fish sandwiches and other inexpensive fish products. Most of these are made with farmed tilapia or catfish that are not good sources of omega-3 fatty acids. We don't know whether this is the reason that fried fish are linked with increased risk of strokes, or whether the unhealthful cooking method cancels out the benefits of any fish.

Polyunsaturated fats in fish are classified by their structure into omega-3s and omega-6s. Omega-3s form prostaglandins that help prevent inflammation that causes heart attacks and strokes. Omega-6s have not been shown to prevent heart attacks and strokes. The fish that are rich sources of omega-3s are those that eat plankton or other fish that have eaten plankton. Almost all deep water fish are rich in the healthful omega-3s.

Of the four most commonly farmed fish (Atlantic salmon, trout, tilapia, and catfish) only trout and Atlantic salmon contain relatively high amounts of omega-3s. In contrast, tilapia (the fastest-growing and most widely-farmed fish) and catfish have much lower concentrations of omega-3s, and their fatty acids are the same as chicken (Journal of the American Dietetic Association, July 2008 and December 2008).

Whether or not a farmed fish contains omega-3s depends on what the fish are fed. Catfish and tilapia can thrive on corn. Since corn is cheaper than fish meal, they are usually fed omega-6 -rich corn, instead of omega-3 -rich fish meal, and thus they have insignificant amounts of omega-3 fats in their bodies. However, salmon and most other farmed fish cannot live on just corn, so they must be fed fish meal that is loaded with omega-3s. All salmon (farmed and wild-caught) are high in omega-3s.

Saturday, January 08, 2011

Being Slightly Overweight Shortens Life

A review of 19 studies covering 1.5 million people shows that being even a little bit overweight shortens your life and the heavier you are, the more likely you are to die of cancer and heart attacks (New England Journal of Medicine, December 2, 2010). Two-thirds of North American adults are overweight or obese.

Doctors measure overweight with a Body-Mass Index (BMI) number: your weight in kilograms divided by the square of your height in meters. A normal BMI is 22.5 to 25. Having a BMI of 27.5 increases your chances of dying from a heart attack by 50 percent, and a BMI over 40 increases risk by more than 400 percent. Similar increases in BMI apply to death from cancers.

No Such Thing as Healthy Overweight Men
"There appears to be no such thing as metabolically healthy obesity," said Dr. Johan Arnlov, author of a 30-year follow up report of 1800 Swedish men showing that overweight middle-aged men are at increased risk for death and heart attacks, even if they do not have metabolic syndrome or diabetes (Circulation, January 19, 2010). Arnlov and his colleagues checked all the men for metabolic syndrome: high blood sugar, high blood pressure, high blood triglycerides (fats), low HDL ("good") cholesterol and a broad waist size (40 inches for men, 35 for women). Metabolic syndrome is the presence of three or more of these risk factors. Follow-up for 30 years showed that the risk of a heart attack was 52 percent higher in overweight men without metabolic syndrome, 74 percent higher in overweight men with metabolic syndrome, 95 percent higher in obese men without metabolic syndrome and 155 percent higher in obese men with metabolic syndrome.

Reducing Overweight a Little Prolongs Life
Being overweight shortens lives because full fat cells produce immune cells that turn on your immunity to promote inflammation that causes diabetes, heart attacks, cancers, arthritis and other diseases. Losing as few as 10 pounds can reduce an over-active immune system to that of a thin person (The Journal of Clinical Endocrinology & Metabolism, June 2010).

Exercise Helps to Prevent Weight Gain
The average person spends a lifetime gaining weight and exercise helps to prevent weight gain with aging. Researchers measured BMI and waist circumference in more than 3,400 men and women and followed them for 20 years. The most-active men gained 5.7 pounds less than those least active, and the most-active women gained 13.5 pounds less than the least-active women (JAMA, December 15, 2010). Many other studies show that exercising regularly helps to protect even those who continue to be overweight.

Message: Being even a little bit overweight shortens lives, and exercise helps to prevent weight gain with aging.

Saturday, January 01, 2011

Exercising on an Empty Stomach Can Both Prevent and Treat Diabetes

One of three North Americans will become diabetic because they eat a high-calorie, high-fat diet that *blocks insulin receptors *to prevent cells from responding to insulin (insulin resistance) *to cause high insulin levels *that constrict coronary arteries *to cause heart attacks. Failure to respond to insulin causes *high blood sugar levels *that cause sugar to stick to cell membranes *to permanently damage the affected cell *to cause blindness, deafness, heart attacks, strokes, amputations and all the terrible side effects of diabetes.

After just a few days on a high-calorie, high-fat diet, cells fail to respond adequately to insulin, blood sugar levels rise, fat deposits in your body, even in muscles, and you gain weight. This causes your muscles to start to lose their ability to store glycogen, the major source of efficient fuel for exercise, and you tire much earlier during exercise.

If you exercise vigorously BEFORE breakfast, you can reduce and even prevent these side effects. Exercising after fasting prevents fat from being deposited in muscles and helps muscles to make more stored sugar (glycogen), the primary efficient fuel for exercise. A study from Leuven, Belgium shows for the first time that "fasted training is more potent than fed training to facilitate adaptations in muscles, and to improve whole-body glucose tolerance and insulin sensitivity" (Journal of Physiology, November 2010). So you are able to exercise longer and harder. If you do not exercise during this period, you gain none of these benefits. If you exercise after eating, these benefits are reduced markedly (Journal of Physiology, April 15, 2005).

When you exercise after fasting, you burn primarily your own body fat for energy. The fat is removed from fat cells and muscle cells. Muscle enzymes burn fat more efficiently and clear further fat from your muscles and fat cells to make your cells more sensitive to insulin. This reverses the cascade described in the first paragraph.

However, fasting before exercising harms training and competitive performance in athletes. The limiting factor to how fast you can move your muscles is the time it takes to move oxygen into muscles. When you fast before exercising, you burn more fat and less sugar. Since sugar requires less oxygen than fat to be converted to energy, your needs for oxygen are greater to burn fat. This slows you down and tires you earlier.

The basic research that showed how muscles convert sugar to energy was done in the 1930s by Diana's father, professor Donald Purdie of Cambridge University in England. He worked with Hans Adolph Krebs, who won the Nobel Prize for Physiology or Medicine in 1953.

It is not established whether athletes should train on a low carbohydrate diet to teach their muscles to burn sugar more efficiently. This would help them to compete at a faster pace. Several studies show that training after fasting increases enzymes that turn sugar into energy. However, training with reduced sugar stores (glycogen) can limit workouts, and this may counteract the gains of fasting before working out.