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18,000 Calories per Day in Race Across America

You need to take in large amounts of food when you exercise for more than a few hours, otherwise you will slow down and eventually have to stop. In the Race Across America, four cyclists alternated shifts as a relay team and completed the race distance of 2800 miles in 6 days, 10 hours and 51 minutes. Each rode up to 10 hours per day in approximately one hour shifts. Even though they cycled only a quarter of the time and distance, they each burned an average 6,420 calories per day, compared to the average for North American men of a little over 2000 calories per day. They ate and drank as much as they could but were able to take in only 4918 calories/day, for a deficit of 1503 calories per day (International Journal of Sports Medicine, July 2010).

Six years ago, a 33 year old bicycle racer used a continuous heart rate monitor to show that he used up more than 18,000 calories per day in the same race. He rode for 20 to 24 hours/day, sleeping no more than 4 hours/day. Yet he could eat only about half that much (9000 calories per day), and he lost 11 pounds of body fat in the nine days of competition (International Journal of Sports Medicine, July-August 2005).

More than 75 percent of North American adults weigh more than they should because they exercise too little and eat too much. These studies show that during long-term continuous intense exercise it is impossible to meet your needs for food, no matter how much you try to eat.


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Dear Dr. Mirkin: Will running or cycling long distances daily, year after year, damage your heart?

No! A study of athletes who participated in extreme and uninterrupted endurance training for up to 17 years, in two to five Olympics, showed no evidence of heart damage (left ventricular weakening, cardiomyopathies) and no heart attacks (Journal of the American College of Cardiology, April 2010). A review of 14 scientific studies shows that elite endurance athletes live much longer than the general population and have a much lower rate of heart attacks (Journal of Science and Medicine in Sport, July 2010).

The concern is that both endurance athletes and people in heart failure have larger than normal hearts. However, a person in heart failure has a large WEAK heart because its muscle is stretched thin by fluid between the fibers, while the large heart of an athlete has huge muscle fibers that are so STRONG that the heart does not have to beat as often, and arteries that are so wide that they are rarely blocked by arteriosclerotic plaques.


Dear Dr. Mirkin: Can taking protein supplements make my muscles stronger?.

Not unless you also cause significant muscle damage by exercising against very great resistance. Doctors in Belgium enrolled 70 patients with coronary artery disease in a program of continuous exercise and lifting weights three times a week for three months. Half also took creatine (protein) pills. Both groups improved equally in strength, aerobic power, muscle performance, health related quality of life, high density lipoprotein cholesterol and triglycerides (Clinical Rehabilitation, published online June 24, 2010).

Obviously the people with heart disease did not lift weights heavy enough to cause significant muscle damage. However, when people exert enough force on their muscles to cause significant muscle soreness on the day after that workout, eating large amounts of carbohydrates and protein can help them recover faster so they can do more heavy lifting which will help them develop stronger and large muscles.

Protein supplements are no more effective than the food from which the protein was taken. Eating a high carbohydrate-high protein meal within a half hour after finishing an intense workout raises insulin levels and hastens recovery (Journal of Applied Physiology, May 2009).

Carbohydrates in the meal cause a high rise in blood sugar that causes the pancreas to release insulin. Insulin drives the protein building blocks (amino acids) into muscle cells to hasten healing from intense workouts. Muscles are extraordinarily sensitive to insulin during exercise and for up to a half hour after finishing exercise, so the fastest way to recover is to eat protein- and carbohydrate-rich foods during the last part of your workout or within half an hour after you finish. You can use either plant or animal sources of protein; both contain all of the essential amino acids necessary for muscle growth.


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June 21st, 2013
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About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities. Read More
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