Low Blood Sugar Causes Mental Fatigue During Competition

Posted November 23rd, 2007 at 3:45 PM by Martha Jones

Section: Nutrition, Race Prep & Recov, Health & Fitness, Exercise

women's runner running on track track and field Athletes can expect to feel fatigued when their blood sugar levels drop. Researchers at Loughborough University, UK showed that athletes who did not take sugar during soccer competition lasting 90 minutes felt more tired, had less competitive desire, and had far lower blood sugar levels than athletes who took a sugared drink every 15 minutes during their game (Scandinavian Journal of Medicine & Science in Sports, October 2007).

Your brain gets more than 98 percent of its energy from sugar in the bloodstream. However there is only enough sugar in the bloodstream to last about three minutes. The liver must constantly release sugar into the bloodstream, but there is only enough sugar in the liver to last eight hours during rest and far less than that during exercise. So athletes who do not take a source of sugar during events lasting more than an hour can suffer the psychological effects of low blood sugar levels what include a mental feeling of fatigue and lowered competitive desire.

In another study, researchers at the University of Waterloo in Canada showed that taking sugar 30 minutes after starting to cycle and every 15 minutes afterwards increases strength, speed and endurance when exercising fairly intensely at 60 percent of maximal oxygen uptake (Journal of Applied Physiology, July 2007).

Muscles burn carbohydrates, fats, and protein for energy. Carbohydrates (sugars) require the least amount of oxygen for conversion to energy, which allows you to move faster with less effort. Athletes use sugared drinks, power bars or candy bars, concentrated sugared gels, cookies and almost any other source of carbohydrates during prolonged competition.

It is possible to take in too much sugar and get a high rise in blood sugar if you are not exercising intensely, but this is rarely a concern for competing athletes. Competition takes great concentration, and eating and drinking are distractions that most athletes limit as much as possible.

This post is written by Dr. Gabe Mirkin, M.D. and used with permission. Dr. Mirkin is board certified in Sports Medicine and has practiced for over 40 years. He has completed more than 40 marathons and was a talk show host of a nationally-syndicated radio program for about 25 years. For more articles by Dr. Mirkin, please check out: www.DrMirkin.com

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