Wednesday, June 30, 2010

Caffeine to Improve Performance in Sports

Caffeine preserves muscle sugar. The limiting factor in racing in any sport is the time that it takes to get enough oxygen into your muscles to burn food for energy, so anything that requires less oxygen allows you to race faster. Sugar stored in muscles, called glycogen, requires less oxygen than fat or protein. Anything that helps you keep sugar in muscles longer gives you greater endurance.

Since caffeine is abundant in our food supply (coffee, tea, colas, chocolate and so forth), most people consider it to be very safe. However, Italian researchers report two bicyclists who took massive overdoses of caffeine and developed severe low blood levels of potassium that can cause irregular heart beats and sudden death (Clinical Journal of Sport Medicine, March 2010).

Very small amounts of caffeine help to preserve muscle sugar and increase endurance. You can increase endurance with as little as a third of a cup of most caffeinated soft drinks. No data exists to show that taking large amounts increases benefit. Up to five cups of coffee a day should not damage healthy people. A cup of coffee contains about 100 mg of caffeine, equal to two cups of tea, three cups of Coca Cola or five ounces of dark chocolate.

Caffeine is a diuretic, but not during exercise. It raises blood pressure only temporarily so this should be of concern only to people with high blood pressure. It can cause irregular heart beats, but is not likely to do so in people with healthy hearts. Caffeine appears to lower risk for diabetes.

Sunday, June 27, 2010

Brown Rice Reduces Diabetes Risk

Researchers at Harvard Medical School report that replacing 50 grams of white rice daily with the same amount of brown rice lowers the risk of type 2 diabetes by 16 percent, and replacing the same amount of white rice with whole barley or wheat lowers diabetes risk by 36 percent (Archives of Internal Medicine, published online June 14, 2010). Those who ate five or more servings of white rice per week were 17 percent more likely to become diabetic than those who ate less than one serving per month. Those who ate two or more servings of brown rice per week were 11 percent less likely to develop type 2 diabetes than those eating less than one serving of brown rice per month.

White rice causes a much higher rise in blood sugar than brown rice does. The higher the rise in blood sugar, the more insulin is released by the pancreas. Excessive insulin production can eventually stop the pancreas from making insulin which increases risk for diabetes. A high rise in blood sugar also causes sugar to stick to the surface membranes of cells. Once stuck on a cell, sugar cannot get off and is eventually converted by a series of chemical reactions to sorbitol that destroys the cell to cause all the side effects of diabetes: heart attacks, strokes, blindness, deafness, kidney damage and so forth.

White rice is "refined" by removing the bran and germ portions of brown rice, which removes fiber, vitamins, magnesium and other minerals, lignans, phytoestrogens, and phytic acid. All of these nutrients may help to prevent diabetes.

All whole grains are seeds of grasses which have a thick outer capsule that requires extensive cooking to make them palatable. Removing the outer coating or grinding whole grains into flour makes the sugars readily available for rapid absorption and higher rises in blood sugar levels. More on whole grains

Saturday, June 19, 2010

Skin Cancers Linked to Human Papilloma Wart Virus (HPV)

Recent research shows that both squamous cell skin cancers and actinic keratoses (pre-cancers) are caused by a combination of ultra-violet light exposure and infection with HPV, the Human Papilloma wart virus (Expert Review of Dermatology, April 2010). Some types of HPV are already known to cause cervical, head and neck cancers.

Most, if not all, actinic keratosis cells are infected with HPV (New England Journal of Medicine, May 15, 2003). Dr. Eggert Stockfleth, of the Charité Hospital in Berlin, found specific types of HPV (21, 5, 8, 16 and 18) that convert normal skin to the pre-cancerous actinic keratoses, which may then progress to become squamous cell carcinomas (Disease Markers, April 2007). To block this process before it begins, Dr. Stockfleth and his team are now developing an HPV-specific vaccine designed for the prevention of these skin cancers.

Chronic exposure to ultraviolet light damages DNA in skin cells. Your immunity tries to repair this damage, but the Human Papilloma wart viruses can prevent your immunity from repairing the DNA. Most of the time when your DNA is damaged, the cells die because they have a programmable cell death called apoptosis. However, the HPV virus prevents DNA from healing and also prevents the programmable cell death that would have removed the damaged cells (Cancer Detection and Prevention, June 2001). Then you develop scaly areas and bumps on your skin called actinic keratoses. With further exposure to sunlight, HPV causes these damaged cells that do not die to develop into squamous cell skin cancers that can spread through your body.

I think that the most effective treatment for actinic keratoses is to use a generic version of imiquimod cream (brand name Aldara) that can cost less than $200 for 36 doses. It enhances your immunity so it can better kill the Human Papilloma wart Virus (HPV). It is applied twice a week for 16 weeks, left on the skin for about eight hours and then washed off. Current treatment by most dermatologists is to destroy the lesions with liquid nitrogen or electrocautery. Surgery is rarely needed for actinic keratoses. However, once an actinic keratosis becomes a squamous cell carcinoma, surgeons usually remove the entire cancer. A pathologist usually checks the removed tissue to see that there is a 360-degree margin of non-cancerous skin around the removed cancer.

Thursday, June 17, 2010

Protein After, Not During, Exercise

High-protein meals eaten immediately after hard exercise have been shown to help athletes recover faster, but the data that taking protein during exercise improves an athlete's performance is extremely weak.

Researchers from the University of Birmingham, UK, showed that adding protein (19g/hour) to a sugared drink does not improve one-hour cycling time trial, maximum power; or post exercise isometric strength, muscle damage (CPK) or muscle soreness (Medicine & Science in Sports & Exercise, June 2010). Protein also does not help athletes cycle faster in a 50-mile time trial (Medicine & Science in Sports & Exercise, August 2006). Most studies showing that adding protein to a carbohydrate drink improves performance were in people working at a fixed rate of effort over a long time, rather than using spurts of energy as athletes do in competition.

Just about everyone agrees that taking in a carbohydrate drink helps improve performances in athletic events lasting more than an hour. In events lasting more than three hours, you also need salt. Calories come from carbohydrates, fats, and proteins. During highly-intense exercise, your muscles use carbohydrates far more efficiently than proteins or fats. So carbohydrates are the calorie source of choice during intense exercise.

All sugared drinks except those with added artificial sweeteners contain eight percent sugar because that is the concentration at which the drinks taste best. You can increase endurance equally with fruit juice, special energy drinks or sugared carbonated soft drinks. Adding caffeine to the drink increases endurance even more because it helps to preserve your stored muscle sugar.

Tuesday, June 01, 2010

Training on Depleted Glycogen Stores?

An article from Australia shows that novice exercisers who train after skipping breakfast have higher muscle levels of glycogen (stored sugar) than those who train after eating breakfast (Journal of Science and Medicine in Sport, May 2010). When you run out of stored muscle sugar, you have to slow down, so having more sugar stored in a muscle should help you exercise longer. The faster you exercise, the greater the percentage of sugar that you use for energy. However, starting workouts with depleted stores of glycogen will not benefit competitive athletes who train for many hours each day, because restricting carbohydrates will cause them to tire earlier and thus do less work.

In another study, researchers asked competitive athletes to train either on a high or low-carbohydrate diet (Journal of Applied Physiology, November 2008). Those training on the low carbohydrate diet had much greater gains in stored muscle sugar and ability to use fat for energy during cycling, although they couldn't train as intensely as the high-carbohydrate group in the first few weeks. However, during the last week there were no differences in training. Both groups improved their one-hour time-trial performances by about 12 percent.

More recent data show that taking sugar during training sessions increases the amount of training an athlete can do without interfering with racing times (Journal of Applied Physiology, February 2009). At this time we do not have enough data to recommend restricting carbohydrates during training, or that it will increase endurance during competition.

CAVEAT! Eating foods or drinks that cause a high rise in blood sugar within an hour before a race will cause you to tire earlier. A high rise in blood sugar causes your pancreas to release huge amounts of insulin which causes you to use up your stored muscle sugar at a much faster rate. When you run out of stored muscle sugar, you have to slow down because it forces you to burn more fat which requires more oxygen. Getting oxygen into muscles is the limiting factor in how fast you can race. Researchers at the University of Hull in the United Kingdom showed that bicycle racers rode much faster 40 kilometer time trials 45 minutes after eating a low glycemic index (GI) pre-race meal than a high glycemic one (Journal of Science and Medicine in Sport/Sports Medicine Australia, January 2010). The low GI meal led to an increase in the availability of carbohydrates and a greater carbohydrate oxidation throughout the time trial. More references