I am not an expert in this area but found the article Add Sugar for Prolonged Hard Exercise by Dr. Gabe Mirkin in the Health & Fitness section of The Epoch Times of November 7-13, 2014, very useful. Below is a summary.
I follow my intuition on what to eat before or after exercise. When you are in touch with yourself, this is usually a safe bet. I don’t eat or drink anything except for coffee (at times) for half an hour before and after I exercise. When I have run the marathon, I have had a few Power Bars, and one time even a sandwich. This is fine for intense or long endurance workouts.
During exercise, muscles use sugar and fat, and, to a lesser extent, protein. For exercise at a relaxed pace, food and drink is not necessary unless hungry or thirsty. I would add that this is true hunger or thirst, and does not apply to times you may be thinking about pizza while you exercise! For intense exercise periods of more than 70 minutes, sugar should be consumed before and while you exercise. There is no advantage to restricting sugar during intense training, as it will not “teach” muscles to get along with less sugar. Carbohydrate loading, used by athletes mostly in the past, also is not effective. Athletes would restrict their carbohydrate intake for four days to “empty” their muscles of stored sugar or glycogen, and then eat a regular diet with extra carbohydrates for three days, all extra carbohydrates beyond what a muscle can store are turned into fat.
Dr. Mirkin wrote that athletesc an store the maximum amount of sugar in their muscles by eating their usual diet and cutting back on training for three days before a competition. A regular meal should be eaten three hours prior to an endurance workout and the workout should not be started on a full stomach. The meal should not be composed of simple sugars.
Sugary foods and drinks cause blood sugar levels to rise. The pancreas releases insulin which causes sugar to enter cells. This leads to low blood sugar levels which can cause dizziness or feeling weak and tired, because the brain uses sugar from the blood. Simple sugars are to be added five to ten minutes before and during long endurance competition. Caffeine can also be used at these times, as it speeds up the rate at which sugar enters muscle cells. A combination of glucose, fructose and sucrose is most effective. (Sucrose is a sugar composed of both glucose and fructose.) However, the need for both glucose and fructose are needed during intense exercise. Sugary drinks can be used throughout intense exercise periods of more than 70 minutes. Sugary drinks, according to the doctor, should be used only during or after exercise.
Contracting muscles take up sugar from blood quickly, so there is no danger or high blood sugar levels (for non-diabetics) if sugary drinks are ingested during exercise. This protection (of not having high blood sugar due to contracting muscles) lasts for up to an hour after the workout is completed.
For endurance events of more than three hours, protein, solid foods and salt should also be ingested.
My third book, Pocket Guide to Fitness, is available on http://www.authorhouse.com and http://www.amazon.com. If you look up my name on those Web sites, you will find my other books The Boy in a Wheelchair and Life, Work and Play: Poems and Short Stories. These two books are on my Web sitehttp://www.louizapatsis.com.