Metabolic Syndrome Linked to Low Magnesium Levels

Metabolic syndrome means you have abdominal obesity, high triglycerides, low HDL (good) cholesterol and high blood pressure, and are high risk for diabetes and heart attacks. It is caused by an inability to respond adequately to insulin. A study from the National Cholesterol Education Program shows that people who are on a diet that is low in magnesium are the ones most likely to suffer metabolic syndrome. (Obesity, Volume 15, 2007).

Nobody really knows why low levels of magnesium prevent cells from responding to insulin. A leading theory is that magnesium is necessary for insulin to act after it attaches to insulin receptors on cells. Before insulin can do its job of driving sugar into cells, it must first attach to special hooks called insulin receptors on the surface of cells. Then it moves sugar into cells by activating an enzyme called tyrosine-kinase. Magnesium is necessary for this reaction to occur.

Another interpretation of this study could be that magnesium deficiency is only an indicator of a very unhealthful dietary pattern that is most likely to cause metabolic syndrome. Since virtually all parts of plants and the animals that eat them contain magnesium, a diet low in magnesium would have to be based on large amounts of white flour, sugar and other highly refined and processed foods. These are also the foods that cause the highest rise in blood sugar. Free weekly newsletter; more on metabolic syndrome

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Asthma or Allergy Sufferers: Cycling is Better than Running

Many people with allergies and lung problems such as asthma should be able to exercise on a bicycle, even when their disease would prevent them from participating in sports that require running. Researchers showed that even people with severe lung disease can ride a bicycle (Medicine & Science in Sports & Exercise, June 2007).

People with obstructive lung diseases such as asthma and chronic obstructive pulmonary disease (COPD) have swelling of the tubes that carry air to and from the lungs. This allows their lungs to fill, but prevents the air from leaving their lungs effectively , so that their lungs are so full of air, they cannot get the air out to get rid of excess carbon dioxide or bring in extra oxygen. Of course, this interferes with their ability to exercise intensely. This study shows that during hard cycling, you can still get rid of excess carbon dioxide and take in adequate oxygen, but running interferes far more with your lung functions.

Exercise is beneficial for everyone and helps to prevent heart attacks, strokes, diabetes, dementia, overweight and other health issues. People with lung problems should get their doctor's permission to start and maintain a cycling program, either on a stationary bicycle or on the road. Free newsletter

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Leg Clots in a Healthy Person: Know the Warning Signs

Leg clots occur without warning with sudden pain and swelling in a leg muscle, usually the calf. This is a particularly dangerous condition because the clot can break lose from the veins in the leg, travel to the lungs and block blood flow to kill a person. In a report in the British medical journal, Lancet, doctors at the London School of Hygiene and Tropical Medicine showed that infections may cause sudden clotting in the leg muscles called Deep Vein Thrombosis. They showed a 20 percent increase in infections, particularly urinary and respiratory, one to two weeks before a person develops clots. This report supports the current theory of inflammation causing heart attacks, strokes, and clotting. Your immunity is good because it is supposed to kill germs when they enter your body. However, if your immunity keeps on being active, it attacks your own body to damage arteries and other tissues.

People at the highest risk for clots are those who are sedentary for a long time, such as in long distance plane flights, and those who suffer cancers. Since infections are common and deep vein clots are not, you should not worry about clots every time you get an infection. However, if after a urinary or respiratory infection, you suffer sudden pain in a leg without any other explanation, check with a doctor immediately to rule out a clot. Journal reference; more on inflammation

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Sore muscles should guide your exercise program

Your muscles should feel sore on some 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 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. Scientist 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 is caused by a buildup of lactic acid in muscles, but now we know that lactic acid has nothing to do 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.

Scientists can tell how much muscle damage has occurred by measuring blood levels of a muscle enzyme called CPK. CPK is normally found in muscles and is released into the bloodstream when muscles are damaged. Those exercisers who have the highest post-exercise blood levels of CPK often have the most muscle soreness. Using blood CPK levels as a measure of muscle damage, researchers have shown that people who continue to exercise when their muscles feel sore are the ones most likely to feel sore on the next day.

Many people think that cooling down by exercising at a very slow pace after exercising more vigorously, helps to prevent muscle soreness. It doesn't. Cooling down speeds up the removal of lactic acid from muscles, but a buildup of lactic acid does not cause muscle soreness, so cooling down will not help to prevent muscle soreness. Stretching does not prevent soreness either, since post-exercise soreness is not due to contracted muscle fibers.

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 to train for muscle burning again until the soreness has gone away completely. Most athletes take a very hard workout on one day, go easy for one to seven days afterward, and then take a hard workout again. World-class marathon runners run very fast only twice a week. The best weightlifters lift very heavy only once every two weeks. High jumpers jump for height only once a week. Shot putters throw for distance only once a week. Exercise training is done by stressing and recovering. Newsletter

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Insulin Levels May Determine Diet Effectiveness

If you are not sure what type of weight loss diet is best for you, you may want to have your insulin levels checked. Researchers at Boston Children's Hospital showed that people with high insulin levels lose weight more effectively on low-refined- carbohydrate diets (Journal of the American Medical Association, May 16, 2007). The researchers measured blood insulin levels one half hour after eating. They then placed overweight patients on either low-fat or low-refined-carbohydrate diets. Those with insulin levels above average at 30 minutes after eating lost more weight on the low-refined-carbohydrate diet.

When blood sugar levels rise too high, the pancreas releases too much insulin. This converts sugar to triglycerides. Then you use up the good HDL cholesterol carrying triglycerides from the bloodstream to the liver. Patients on the low-refined- carbohydrate diet had a much greater rise in the good HDL cholesterol and a much greater lowering of triglycerides. Those on the low-fat diet had a greater lowering of the bad LDL cholesterol.

Another study from City College of New York showed that after eating a fatty meal, obese people produce more insulin than thin people do. Blood insulin levels of thin and obese people rise equally high after eating refined carbohydrates. Unlike thin people, obese people have a high rise in insulin after eating a fatty meal. Insulin affects the brain to make a person hungry so he eats more. More on weight loss and nutrition; free newsletter on fitness, nutrition and health.

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Rethinking the Maximum Heart Rate Formula

For more than forty years, fitness instructors have based exercise prescriptions on the maximum heart rate formula of 220 minus your age. A study from Oakland University in Rochester, Michigan shows that this formula may be wrong (Medicine and Science in Sports and Exercise, May 2007). The researchers found that the original formula overestimated the maximum heart rate for younger exercisers and underestimated the maximum rate for older ones. The new formula they recommend is 206.9 - (age x .67) = maximum heart rate.

Athletes train by taking a hard workout on one day, feeling sore on the next day, and then going easy for as many days as it takes for the soreness to go away. Then they take another hard workout and repeat the cycle. Most exercise physiologists and coaches tell their conditioned athletes to raise their heart rates to 80 to 100 percent of their maximum when they take a hard workout. For people who exercise for fitness, a hard workout usually means exercising at 60 to 80 percent of maximum heart rate.

However, the maximum heart rate formulas are set by averages of large populations. Your own maximum heart rate is determined by your fitness level as well as your age. Your legs drive your heart, not the other way around. When you start to exercise, your leg muscles contract and squeeze blood from your veins near them. Then when your leg muscles relax, your veins open and fill with blood. This alternate contacting and relaxing of muscles pushes extra blood toward your heart. The increased return of blood to your heart speeds up your heart. People with stronger muscles pump more blood towards their hearts and therefore can get a faster heart rate.

Since there is huge variation between individuals ranging from competitive athletes to novice exercisers, you would be better off setting your workout level by "perceived exertion", rather than by any formula based on averages. "Perceived exertion" means that your brain interprets how hard your are exercising, and you can respond to these signals. As you exercise more intensely, you become short of breath and your muscles start to burn and hurt. You can interpret your own effort and discomfort levels to decide how hard you should work on a hard day or an easy day.

People who are just starting an exercise program or who do not exercise regularly should use much lower levels of effort. They should never try to get to their maximum heart rates because they are the ones most likely to suffer heart attacks during exercise. Start any new exercise program slowly and build up your level of fitness gradually. More

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Carbohydrate Loading Benefits Can Last Several Days

An important part of your energy for vigorous exercise comes from the sugar stored inside muscle cells. When you run out of stored muscle sugar, your muscles may hurt and be more difficult to coordinate. Carbohydrate loading is a technique athletes use to increase the stored sugar in their muscles. Four days before a competition, they exercise vigorously and then for the next three days, they eat their normal diet plus large amounts of extra carbohydrates in foods such as bread, spaghetti and potatoes. A recent study shows that after carbohydrate loading, the muscles will be full of extra sugar for up to five days (European Journal of Applied Physiology, February 2007).

At three, five and seven days of limited activity after the loading process, the researchers cut out pieces of muscle and analyzed the sugar content. Only at seven days post-loading did muscle sugar concentrations drop significantly. This means that if your competition is delayed, you can expect the effects of carbohydrate loading to last up to five days.

Eating a high-carbohydrate meal, such as pasta, the night before a competition helps to load muscles maximally with sugar. The pre-race meal cannot load muscles as it takes at least 10 hours to refill muscles with sugar. However, on race day, the athletes may pay a price because high carbohydrate, low-fiber foods can cause constipation. So they have to stand in long lines, waiting to use the portable johns. Had they eaten their carbohydrates in high-fiber foods the night before, they could have concentrated better on their upcoming competition. More

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