Thursday, February 24, 2011

Cycling Does Not Weaken Bones

A recent article from France may explain why some top bicycle racers have low bone densities, indicating an increased risk for breaking their bones (The Physician and Sportsmedicine, October 2010). Nobody has ever shown that bicycling or any other type of exercise weakens bones. I discussed this in detail in my 9/12/10 eZine.

We may now have an explanation for the weak bones found in some elite bicycle racers: they could have taken glucocorticoids to help them ride faster. These drugs, taken for just a few days, take calcium out of bones to cause low bone density, osteoporosis and bone fractures. Examples of glucocorticoids include Cortisone, Dexamethasone, Hydrocortisone, Prednisolone and Prednisone.

Female athletes who were not competitive bicycle racers were given 50 mg of prednisone per day for one week and then tested to see how long they could continue cycling at 75 percent of their maximal output (VO2max). They were able to last 66.4 minutes after a course of prednisone, compared to only 47.9 minutes after placebo (European Journal of Applied Physiology, November 2009). That's an incredible 30 percent increase in endurance time.

The limiting factor in how fast you can ride a bicycle or run, ski or skate over long distances is the time it takes for oxygen to get into your muscles. Therefore anything that decreases your need for oxygen will help you to move faster over distance. Sugar requires less oxygen than fat or protein to be converted to energy by your muscles. So anything that causes your muscles to burn more sugar, and less fat, makes you faster. Corticosteroids markedly elevate blood sugar levels. For example, a normal blood sugar is below 100. After taking steroids, your blood sugar can rise over 300.

Glucocorticoids, taken in pills or injections, are banned by the World Anti-Doping Agency (WADA) during competition. Athletes get around the rule restricting corticosteroids by claiming that they have *asthma treated with steroid inhalers, *certain skin disorders treated with steroid creams, or *muscle or joint injuries, immune disorders or diseases treated with steroid creams, pills or injections.

People should take glucocorticoids only if they need them to treat a serious, usually life-threatening disease. Not only can glucocorticoids cause permanent osteoporosis, they also can increase risk for diabetes, high blood pressure, heart attacks and fat gain. They are very different from the anabolic steroids that some athletes take to grow larger and stronger muscles.

Wednesday, February 09, 2011

Full Fat Cells Cause Heart Attacks and Strokes

A diet of fruits, vegetables and nuts lowers the bad LDL cholesterol in two weeks by 33 percent, far more than the same diet with added grains and low fat diary (23 percent), and even more than by the National Cholesterol Therapeutic Step-2 diet recommended by doctors for people with high cholesterol (7 percent). Even more important, the ratios of LDL/HDL cholesterol are reduced by 24 percent, 12 percent, and 5 percent respectively (Epidemiology, March 2006).

This study by David Jenkins and many other studies show that the most effective way to lower high cholesterol and blood pressure, prevent heart attacks and prolong life is to avoid taking in more calories than you burn. Limiting food intake to just fruits, vegetables and nuts makes it very difficult to meet your needs for calories. You have to eat all day long to get enough calories just to maintain your weight. This diet is almost the same as what human ancestors ate four to seven million years ago before they split off in development from apes, who eat almost the same way in the wild today.

Further evidence that extra calories cause heart attacks comes from the fact that reducing your intake of calories by one third and eating nothing but fatty meats and diary products will cause your blood cholesterol level to go down (European Heart Journal Supplements, 1999;1(S):S19-S23). Saturated fats are broken down in your liver to two-carbon acetyl units. If you take in more calories than you need, the acetyl units are used as building blocks to make cholesterol and your blood cholesterol level rises. On the other hand, if you are not taking in extra calories, the acetyl units are burned for energy and do not raise cholesterol.

The fruit-vegetable-nut diet is extremely low in significant amounts of starch because humans did not eat large amounts of grains until the agricultural revolution about 10,000 years ago. By adding whole grains and animal products to the fruit-vegetable- nut diet, humans suddenly increased their caloric intake dramatically. Their bodies were used to trying to get every calorie they could possibly get from the food that they eat. Now they could get all the calories they needed. As long as they were very active physically, they could compensate for the extra calories that they could take in and use. However, as soon as humans stop being physically active, they start to store extra calories as fat and it is the extra fat that causes much of modern day disease.

Adding low-fat dairy products, whole grains and dried beans to a fruit-vegetable-nut diet creates a diet that is low in saturated fat and low in cholesterol. This is the basis of the therapeutic diets recommended by most physicians to help prevent heart attacks today, yet these diets are significantly less effective than the fruit-vegetable-nut diet that forces severe calorie restriction.

The most unhealthful diet is one that allows you to take in more calories than you need *so you store more fat in your muscles, *fat in cells blocks insulin receptors, *your cells stop responding to insulin, *your blood sugar rises, *sugar sticks to cell membranes to damage cells and cause *diabetes, heart attacks, strokes, cancers, and premature death.

If you have high cholesterol, high blood pressure, heart disease or diabetes, try limiting your diet to fruits, vegetables and nuts for just two weeks. It is likely that your cholesterol and blood pressure will drop significantly in that short time, and you will have identified the source of your problem.

Saturday, February 05, 2011

Muscle Cramps in Exercisers

Muscle cramps are common during very intense exercise and occur far less often during less-intense training, because the most common cause of muscle cramps in exercisers is muscle damage from all-out pressure on the muscles.

Cause: Muscle Damage
The leading theory is that most cases of muscle cramps in serious exercisers and athletes are caused by an exaggerated "stretch reflex". When you stretch a muscle, it pulls on its tendon. Stretch reflex nerves in that tendon send a message back to the spinal cord (not the brain), and then the "stretch reflex" in the spinal cord sends a message along nerves from the spine to cause the muscle to contract. During sustained extreme pressure on the muscles, the muscle retains its contraction to form a cramp. A study from South Africa showed that the most likely cause is muscle fatigue or tearing of the muscle itself (Medicine & Science in Sports & Exercise, July 2005).

If this is true, muscle cramps during endurance events can be prevented by slowing down when you feel excessive soreness in one muscle group or straining in a muscle. Of course, competitive athletes will not do this, and they pay for it with muscle cramps.

The researchers studied triathletes and found that most of the time, the muscles cramps were not caused by dehydration, thyroid disease, blocked blood flow, nerve damage, or mineral abnormalities of calcium, sodium, magnesium or potassium. The athletes with cramps had normal electrolytes, and did not lose more fluid during exercise than those who did not suffer cramps. The researchers showed that the most likely cause is muscle fatigue or tearing of the muscle itself. Electromyograph (EMG) studies at one to five minutes showed markedly elevated electrical activity of the nerves controlling the cramped muscles. A review of the scientific literature shows the most common cause of muscle cramps appears to be muscle damage (Journal of the American Academy of Orthopaedic Surgeons, July 2007).

What to Do When a Cramp Strikes
Almost all racers who experience exercise- associated muscle cramps do not suffer from disease and can usually prevent cramps by slowing down when one muscle group starts to feel tight or excessive soreness. You do this by switching pressure from the cramped leg to the uncramped one. A bicycle racer moves most of his pressure to the pedal of the uncramped leg. A runner shortens the stride of the cramped leg. Continuing to put pressure on the cramped muscle can rupture the muscle.

Dehydration or Lack of Minerals Less Common
Some cramps are caused by low mineral or fluid levels (The Japanese Journal of Clinical Pathology, November 2007). However, for the vast majority of people who suffer exercise- associated muscle cramps, blood levels of sodium, potassium, calcium and magnesium are normal. Research in athletes after they ran in 52-mile races showed that the runners who suffered cramps had the same level of dehydration and blood mineral levels as those who did not get muscle cramps.

Lack of Salt
The most common mineral cause of muscle cramps in exercisers is lack of salt, according to a report from the University of Oklahoma (Sports Medicine, April-May 2007). The authors cite studies of tennis and football players, showing that crampers tend to be salty sweaters; and of triathletes, where those who cramp lost more salt during a race than their peers who did not cramp. They found that intravenous saline can reverse cramping, and that more salt in the diet or in sports drinks can help to prevent heat-associated cramping.

For many years I have recommended eating salted peanuts or other salty foods during heavy exercise, but other doctors believe that extra salt may raise blood pressure. If this is a concern for you, get a wrist cuff monitor and check your blood pressure every day. You are likely to find that your blood pressure goes down, not up, with regular exercise even when you add salt.

Non-treatments
Nobody has shown consistent benefit from any of the most common treatments: multivitamin pills; mineral pills with calcium, zinc, magnesium, salt and/or potassium; massage or chiropractic manipulation; drinking large amounts of water; dietary manipulations; or bio-mechanical stretching and strengthening.

Non-causes in Serious Exercisers
Known medical causes of muscle cramps are extremely rare. If you suffer from recurrent muscle cramps, you may need special tests for pinched nerves, Parkinson's disease, low thyroid, diabetes, narrowed arteries from arteriosclerosis, low blood mineral levels, metabolic diseases that cause muscle damage, or side effects of drugs used for high cholesterol, high blood pressure or diabetes, diuretics, oral contraceptives or alcohol (Neurology 2010; 74: 691-96).

Medications
Quinine should not be used because it can damage blood cells. Some studies show that gabapentin (an anticonvulsant), diltiazem ( a blood pressure medication), or B-complex vitamins may help to relieve muscle cramps in some people (Journal of Clinical Pharmacology, 1998;38:1151).

Warning Signs
Before a cramp develops, you will probably feel the muscle pulling and tightening. If you slow down, the pulling lessens, but if you continue to push the pace, the muscle goes into a sustained cramp and you have to stop exercising to work the cramp out. Further evidence that muscle damage is the cause of the cramp is that the muscle often hurts for hours or days afterwards. You may be able to prevent cramps by exercising more frequently but less intensely and for shorter periods of time, but most racers do not want to do this.

Sugar
There is some evidence that taking sugared drinks or foods during prolonged exercise helps to maintain endurance and muscle integrity which helps to prevent cramps. Take a source of sugar every 30 minutes or so during vigorous workouts or races, and back off if you feel a group of muscles pulling or tightening during exercise.

Lack of Vitamin D
A leading cause of muscle damage, soreness and slow- healing injuries in athletes is lack of vitamin D. If you suffer frequent cramping and your muscles feel sore or you keep on being injured when you exercise, get a blood test called D3. If it is below 75 nmol/L, your problems may be caused by lack of vitamin D and be cured by getting some sunshine or taking at least 2000 IU each day of the very inexpensive vitamin D3.

Occasional Cramps Not Harmful
Most racers and serious exercisers accept that occasional cramps will occur, and will cause no long-term harm.