11) EXERCISE AND TYPE 2 DIABETES
g) Exercise Myths
Some exercise "experts" incorrectly says that anaerobic exercise burns more calories than aerobic exercise because the end result is lactic acid rather than carbon dioxide and water. In truth the lactic acid produced by anaerobic exercise is sent to the liver to be converted back to blood sugar to ultimately be reduced to carbon dioxide and water, so the calories burned remain the same. The human body has evolved through millions of years to be very efficient at utilizing all available calories.
Another "myth" about exercise and weight loss is that you have to be very careful or your body will burn muscle instead of fat and your muscle mass will suffer. The myth of muscle being burned instead of fat came about from studies that show that extremely strenuous exercise over very long periods will deplete all the body's stores of carbohydrate and the muscles will begin burning protein. Because there are substantial stores of carbohydrate ("glycogen") in the liver and muscles that can be used for energy during exercise, it requires really strenuous long term exercise before protein begins to be burned by muscle cells, typically at least 60 minutes of very high intensity exercise. Only this prolonged high intensity exercise will result in protein burning. But at that point the carbohydrate stores will run out and muscles will begin to burn their own protein. Muscles cannot transfer fat from fat cells and burn the fat, it takes too long. Fat cannot provide "fast" energy; it only provides "slow" energy.
But, even if protein burning does occur, this protein burning is only for the short term. When the muscles can rest (such as when someone is sleeping) the muscles pull protein from the food in the intestines and rebuild their protein levels, typically to higher levels than before the strenuous exercise. At the same time as the protein is rebuilt, the carbohydrate stores in the muscles and in the liver are rebuilt from the carbohydrates being eaten. During this time body fats can be utilized as the primary source of "slow" body energy. Now here is where diet and body fat gets related to one another. If any person's food has large amounts of calories in it, all the energy required for day to day living gets pulled from the food and doesn't get pulled from the body's fat stores. Once again, it is calories in versus calories out.
If the individual is in ketosis and is not eating carbohydrates, the body can only replenish the store of carbohydrate from muscle cell and food protein, it cannot replenish the carbohydrate stores from internal fat or ingested fat; it's just a chemical impossibility. The body has an internal mandate to keep the stored carbohydrates at a decent level. If an individual is keeping the amount of food eaten to a low level in order to lose weight (or is eating large amounts of fat calories with smaller amounts of protein calories and no carbohydrate calories, i.e. the Atkins diet), the muscle cells will degrade their own muscle proteins to provide carbohydrate during exercise. So "protein burning" and muscle wastage during exercise is very real for individuals in ketosis.
The reverse is also true. If a dieting person eats less than 20% of their calories in protein and has a vigorous exercise program that includes weight lifting and resistance training, then the body will lose muscle mass as well as fat mass. We recommend that anyone doing a vigorous weight liftng program or resistance training ingest at least 40% of their calories from protein.
There are also a lot of myths (especially in weight lifter magazines) about timing the ingestion of various carbohydrate/fat/protein mixes with exercise to maximize weight loss or muscle mass gain. Don't believe any of them. The carbohydrate storage system of the muscles and the liver form a huge buffer which prevents any meaningful effect from occurring (unless someone is in ketosis). Also note that there is a level which is too much exercise. Professional athletes, triathlon competitors, and the "super fit" that exercise like maniacs 40 hours a week actually die at about the same average age as those who don't exercise at all. The body's cells will just repair themselves so many times, and then they basically wear out.
It is also not necessary to stretch before exercise. Research shows that stretching before exercise actually increases your chance of getting injured and may decrease your workout performance. The best way to prepare your body for physical activity is with a 3-5 minute warm up of easy walking, light cycling or gentle movement. Stretching is best done very slowly after exercise as part of a cool down cycle.
Current Chapter: 11) EXERCISE
a) Introduction
b) Exercise and low Blood Sugar
c) Exercise and Weight Lose
d) Aerobic Exercise and Heart Disease
e) Exercise and Peripheral Arterial Disease
f) Proper Resistance Training
g) Exercise Myths
h) Exercise, Stress and Diabetes
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