Drinks containing glycerin may help you to exercise longer, particularly in hot weather. Exercise causes you to sweat and lose a lot of water. The lack of water makes you tired. If you take something to help your body retain water, your body will hold more fluid, and you will be able to exercise longer.
Glycerol is one of the body's building blocks for fat. When extra glycerin is taken by mouth, it increases tissue levels of glycerol and helps you to store extra water.
Studies at the University of New Mexico and at the U.S. Army Institute of Environmental Medicine in Natick, Mass., show that taking glycerin and extra water before exercise will make you start to sweat earlier and produce more sweat. This keeps your temperature from rising too high so you can exercise longer.
Scientists added 70 grams of glycerin to three glasses of water and three glasses of orange juice and had the subjects drink this mixture 2 1/2 hours before exercising. The athletes felt bloated for an hour but had no trouble during exercise.
So far, research has shown glycerin to be safe, effective and cheap. Fewer than 2 percent of the subjects develop headaches and nausea, and it costs less than a dollar a day, but the companies that sell it are concerned about lawsuits from potential side effects, so they sell it only to people doing research. The major manufacturers of sports drinks are doing research on glycerin.
Q: I'm 62 and have trouble lifting my 2-year-old grandson. Am I too old to start weight-lifting?
A: Lots of young people lift weights and push on special strength-training machines, but very few older people do, even though they need the training more than younger folks.
Your muscles are made up of millions of individual fibers, just like a rope is made up of smaller threads. Each muscle fiber is activated by a single nerve that gets its messages from the brain. As you age, nerve cells wither and die. When a nerve dies, the muscle fiber that is attached to it also dies. With aging, each muscle has fewer fibers to do the same job, so it becomes weaker.
To retain strength with aging, you have to enlarge and strengthen the remaining muscle fibers. The only way to do this is to exercise against increasing resistance, but with aging you have to be more careful when you train for strength. Your muscles are weaker than when you were younger and are more %% likely to be injured. Lifting heavy weights can also cause blood pressure to rise considerably, and blood vessels that are already weakened by aging may burst, or a weak heart may beat irregularly. This will not happen to people who have normal hearts and blood vessels.
Anyone who is over 50 and would like to become stronger should check first with their doctor. You can join an athletic club and learn how to use special strength-training machines. Pick 10 to ,, 15 exercises and do each twice a week, using the heaviest weight that you can move comfortably 10 times in a row without straining and without losing form.
Q: I've heard you say that people should use sunscreens 365 days a year. If I'm not going to be in the sun, what good is sunscreen?
A: Excessive exposure to sunlight causes skin cancer, but a tTC precancerous lesion called an actinic keratosis appears long before the cancer. Applying sunscreens daily can cause many actinic keratoses to disappear before they become cancers.
Physicians in Australia studied 600 people who had severely sun-damaged skin. Each participant had at least one actinic keratosis diagnosed by analyzing the tissue after surgery. Half were given a cream containing a sunscreen, while the rest were given a cream that contained no sunscreen. Both groups were told to avoid the sun as much as possible.
At the end of the summer season, those who applied the placebo had at least one additional actinic keratosis, which was removed by surgery. Those who applied the sunscreen had a decrease in actinic keratoses.
Continuous application causes the sunscreen to stick to your skin so it will not be sweated or washed off. Dr. Mirkin is a practicing physician in Silver Spring specializing in sports medicine and nutrition.