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Maximum Heart Rate Lower in Athletes

A study from Liverpool, England shows that the maximum heart rate for athletes is lower than for aged-matched sedentary people. At first glance, this makes no sense because you would think that the faster you heart can beat, the more blood your heart could pump and the better an athlete you would be. However, a stronger heart pumps more blood with each beat, so stronger hearts don't have to beat as often. This means that as you become more fit, your maximum heart rate will get lower, not higher.

Virtually everyone agrees that heart rate depends on the amount of blood pumped toward it by exercising muscles. When you contract your leg muscles during exercise, muscles squeeze veins near them to pump blood toward the heart. Then when leg muscles relax, the veins fill up with blood. The pumping action of leg muscles during exercise forces extra blood to the heart, which causes the heat to beat faster and contract stronger. This is known as the Bainbridge reflex. We know this is true because we are able to transplant hearts. If nerves to the heart regulated heart rate, the heart would not be able to control its rate of beating since the nerves are cut during the transplant.

Since the strength of leg muscles determines the fastest that your heart can beat and still pump blood, you might expect that athletes with stronger muscles would have faster heart rates. However, they don't. The researchers at John Moores University in Liverpool showed that athletes have lower maximum heart rates than sedentary people (International Journal of Sports Medicine, January 2008). The maximum heart rate of male athletes was calculated to be 202 - 0.55 × age, and for female athletes, 216 - 1.09 × age. Both weight lifters and runners had similar maximum heart rates, which were significantly lower than the age-matched sedentary people. The athletes have hearts that can pump more blood with each beat than the hearts of sedentary people, so they do not beat as often.

Remember that all formulae for maximum heart rates are based on averages. They can be used to help you plan and monitor your exercise program, but should not be interpreted as absolute limits or goals. Your maximum heart rate may differ from these averages.

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Dear Dr. Mirkin: Is obesity inherited?

Nobody has really proven why some people eat a lot and are skinny, while other eat little and are fat. The simplistic explanation of eating less and exercising more to control weight doesn't work for all people. Researchers at Maastricht University in the Netherlands think that some people burn a greater percentage of the food that they eat than others (American Journal of Clinical Nutrition, January 2008). They showed that people who are fat burn a lower percentage of the calories that they take in than those who are skinny. They used deuterated palmitic acid, given with breakfast, to measure percentage of calories burned.

Future studies must explain whether some people are genetically destined to be fat because they burn fewer calories, or whether any person who becomes fat will then burn fewer of the calories they take in. That could explain why overweight people continue to get fatter even if they eat less than their thinner peers.

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Dear Dr. Mirkin: Should weight lifters take in fluid during a workout or competition?

Recent research show that long-distance runners and cyclists do not have their performances impaired by lack of fluids until they are so dehydrated that their blood volume is decreased. These endurance athletes suffer from lack of muscle sugar long before they feel any effect from dehydration. This led researchers at the University of Connecticut to ask if weight lifters have their strength impaired by dehydration (Medicine and Science in Sports and Exercise, October 2007). Their answer is a resounding "yes". Their subjects started to falter when lifting their third set of ten. However, they were at least 2.5 percent dehydrated, which is a loss of fluid equal to more than four pints. The same advice applies for weight lifting and endurance sports: all athletes should have both fluid and sugar during competitions lasting more than an hour.

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June 25th, 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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