Exercise benefits: new studies

This month's literature shows that exercise prevents cancers and helps to improve mental function with aging. Researchers from the University of Melbourne in Australia show that adults with memory impairment improve mental function after a six-month exercise program (JAMA, September 3, 2008). Another study, from Tokyo, shows that adults who exercise regularly and are active are less likely to develop a range of cancers (American Journal of Epidemiology, August 2008). The researchers followed 80,000 Japanese adults for up to ten years. Those who were more active had reduced risk for developing any type of cancer, particularly cancers of the colon, liver, pancreas or stomach.

This benefit was greatest in those who were not overweight, showing that exercising enough to control your weight is better than just exercising. Exercise lowers body fat and being overweight is associated with increased cancer risk. Furthermore, exercise can activate immune cells to hep prevent cancer. It also lowers certain sex hormones and insulin-like growth factors that can feed the growth and spread of tumors. Newsletter

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Nitric Oxide May Help Athletes

Should you believe claims that nitric oxide supplements will enlarge muscles and increase endurance? Actually, there are no products that contain nitric oxide because it is too unstable. However, supplements containing arginine (an amino acid) in combination with another blood vessel widener, alpha- ketoglutarate, can stimulate the blood vessels to increase production of nitric oxide. This dilates blood vessels that bring blood to muscles. Several studies show that the nitric oxide releasers may help athletes exercise longer, but the data are weak, sparse and not very impressive. If you take these supplements and do not exercise to your maximum, you are wasting your money. However, if you are already exercising as hard and as fast as you can, taking these supplements may let you do more work, which can make your muscles stronger (Medicine & Science in Sports & Exercise, December 2000).

Promoters of these supplements recommend doses of 6,000-10,000 mg per day and most athletes who use them take far more than that. Half of the athletes who took double the recommended dose suffered adverse side effects, usually nausea, stomach cramps or diarrhea. High doses may drop blood pressure which would harm performance. Blood pressure usually rises with exercise; a person with resting blood pressure of 120/80 can expect it to rise to 200/80 while jogging.

Prescription nitric oxide simulators such as Viagra can benefit men who have difficulty achieving or maintaining erections. Exercise, by itself, raises blood levels of nitric oxide (American Journal of Hypertension, August 2007). So if you want your arteries to make more nitric oxide, go out and exercise.
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Monosodium Glutamate: Weight Gain?

Many people still avoid MSG as the culprit in "Chinese restaurant syndrome", even though no scientific studies were ever able to show that MSG causes headaches, flushing, tingling or anything else. However, a recent study of Chinese peasants suggests that MSG may cause weight gain (Obesity, August 2008). The subjects were divided into three groups, based on the amount of MSG used, and those in the group that ate the most MSG were nearly three times more likely to be overweight than non-users. Previous studies on mice and rats found the same effect. Dr. Ka He, the lead author of the study at the University of North Carolina, concludes that MSG makes food taste better so people eat more.

It's not easy to avoid MSG even if you read food labels. Everyone eats significant amounts of monosodium glutamate because all foods that contain protein have a building block amino acid called glutamic acid which is converted in the body to glutamate. More

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Salt Helps to Retain Fluid

Researchers at Loughborough University in Leicestershire, UK show that the salty drinks help your body to retain fluid and therefore increase the time that you can exercise, particularly in the heat (European Journal of Applied Physiology, July 2008). They fed drinks of four different salt concentrations to competitive cyclists. The higher the concentration of salt, the less urine they produced. This shows that salt helps their bodies to retain water so they will have more fluid available to cool their bodies in the heat. However, this study showed that it did not improve their performance.

In 1942, the United States Government asked James Gamble of Harvard Medical school to set up guidelines for soldiers who must fight in the heat. His classic, impeccable experiments are still the basis for recommendations today for fluid and mineral replacements for athletes. He showed that the only mineral that needs to be replaced during exercise or other hard work in hot weather is sodium. So when you exercise in the heat, make sure that you take in extra salt, either in a sports drink or in salted foods such as peanuts or pretzels. If you are concerned about the effect of this extra salt on your blood pressure, buy a simple blood pressure cuff and take your blood pressure weekly, just to make sure that you are not taking too much salt or exercising too little.

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More exercise, less high blood pressure

People who continue to exercise throughout their lifetimes are far less likely to develop high blood pressure and the more they exercise, the less likely they are to develop high blood pressure (Journal of Hypertension, June 2008). In various studies, up to 91 percent of the North American population suffers from high blood pressure which puts them at markedly increased risk for strokes, heart attacks, kidney damage and arteriosclerosis. Virtually all scientists agree that this frightening incidence of high blood pressure is caused by lifestyle, and the major lifestyle factors are lack of exercise, obesity, and eating too many calories, refined carbohydrates and saturated fats.

For some people, but not all, increased intake of salt also contributes to high blood pressure. However, if you exercise, you need to take in extra salt since salt is the only mineral that you lose in large amounts through sweating. Low salt levels can cause muscle damage, fatigue and depression. Salt deficiency can also raise high blood pressure because it causes your kidneys to produce large amounts of renin and your adrenal glands to make more aldosterone. These hormones constrict arteries to raise blood pressure.

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Measure Abdominal Fat, Not Just Weight

Researchers at the University of Michigan report that not all people who are fat are at high risk for heart attacks (Archives of Internal Medicine, August, 2008). They showed that 51 percent of overweight adults (36 million Americans) have normal blood pressure, cholesterol and blood sugar, while 25 percent of normal- weight Americans (16 million) have high levels of at least two of these tests. The media picked up this study with headlines such as "Better to Be Fat and Fit Than Skinny and Unfit" (New York Times, August 19, 2008).

However, the entire study is flawed. The authors measured overweight, not abdominal obesity. If you just compare weight to height to define obesity, more than 50 percent of professional football players would be obese, and they are not. I am sure that the study would show the far more harmful effects if the authors had measured abdominal obesity rather than just weight. Storing fat primarily in your belly can predict premature death. It means that a person's insulin levels are very high and high insulin levels mean that your body is not responding to insulin so you are at increased risk for a heart attack, stroke, kidney damage, arteriosclerosis and all the other harmful side effects of diabetes.

Other studies do show that it is better to be fat and fit than out-of-shape at any weight. Steven N. Blair of the University of South Carolina showed that adults over 60 who had higher levels of fitness lived longer than unfit adults, independent of how fat they were (JAMA, December 5, 2007). He showed that fat people who were able to run on a treadmill longer than unfit, fat people had better blood tests and fewer heart attacks and deaths.

How should these studies affect you? If you are overweight, you increase your risk for heart attacks, strokes, cancers and premature death. If you store large amounts of fat primarily in your belly, you are at such great risk for premature death that you should check with your doctor and probably get a thallium stress test to see if your coronary arteries are already blocked. If they are not blocked, start a supervised exercise program and diet to lose weight and become fit. If your coronary arteries are already blocked, you will need immediate counseling about future treatment.
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Saturated fat risks cancelled by exercise

The Masai of Kenya and Tanzania eat the same type of high animal-fat diet as North Americans, but they have a very low incidence of heart attacks. In spite of the large amount of saturated fats in their diets, they have lower body weights, waist measurements, blood pressures and cholesterol levels (British Journal of Sports Medicine, July 2008). This is explained by the fact that the average Masai burns 4,000 kilocalories a day, which is roughly equal to walking 12 miles every day (this number includes the amount you burn for normal daily activities such as breathing and sleeping).

Saturated fat is the dominant fat in meat, chicken and whole milk dairy products. It raises cholesterol only when a person takes in more calories than he burns. A high-meat diet does not cause heart attacks in people who get a lot of exercise. Saturated fats are broken down by your body into two-carbon units. If you are getting too many calories, your liver converts these two-carbon units into cholesterol. If you are not getting enough calories, your body burns these units for energy.

When you take in more calories than your body needs, you store the excess as fat. Full fat cells release cytokines into your bloodstream, and they turn on your immunity. Your immunity is good because it protects you from infection, but if it stays overactive, it starts to destroy your body including your heart and blood vessels. The bottom line: if you eat much saturated fat, be sure to get plenty of exercise.
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