Most older people will find this hard to believe, but when they injure their muscles during exercise, they heal just as quickly as younger people do.
Your muscles usually feel sore on the day after you exercise vigorously. The soreness is caused by direct damage to your muscle fibers. Most people heal from this damage within 48 hours. Competitive athletes know this and usually train hard on one day and then do not exercise intensely again until after the soreness disappears at least 48 hours later.
In a study reported in the Journal of Gerontology, researchers found that older people recovered from strenuous exercise just as fast as college students did. Older people can train like younger people, but they should train less frequently and less intensely because they have fewer muscle fibers.
Muscles are made up of thousands of individual fibers, similar to how a rope is made of many smaller threads. Each muscle fiber is stimulated by a single nerve. As you age, your nerves start to die and disappear. When you lose nerves, you also lose function in the fiber stimulated by that nerve. Thus, older people have fewer fibers and weary muscles and are more likely to injure themselves when they try the same work outs that younger people can do with relative ease.
The good news is that an older person's muscle fibers are just as trainable as those of a younger person. As you age, you can still become stronger and faster and increase your endurance as long as you stop exercising when you feel pain and allow your muscles to recover from hard workouts.
Q: My teen-age son is very overweight. Does that mean future health problems?
A: According to a recent report in the New England Journal of Medicine, being overweight as a teen-ager means a shorter life span and a greater chance of suffering from heart attacks, arthritis, colon cancer and gout.
Being fat as an infant or child under the age of 12 has only a weak association with being fat as an adult. An infant is fat only when he or she is fed too much. Most fat children lose their baby fat when they reach puberty.
Obesity is usually genetic and influenced more by the metabolism you inherit than by how much you eat. If you are overweight after puberty, after your hormones have settled, you are very likely to be an overweight adult.
You probably should not try to restrict an overweight child's food before puberty. That can reduce his height as an adult.
Q: Health experts (including you!) say we should eat a low-fat diet that includes beans. But beans give me gas. Any solutions ?
A: For more than 20 years, I've used baking soda, also called sodium bicarbonate, to remove the substance in beans that causes gas. Soaking beans in baking soda also helps to cook them faster and improves their flavor.
Scientists at the Institute of Human Nutrition of Central America and Panama found that soaking beans in a solution of 0.5 percent sodium bicarbonate and 2.5 percent potassium carbonate resulted in the shortest cooking time and the highest quality of protein in the beans.
Here's what I recommend:
Buy several different types of dried beans. Place them in a large kettle and cover them with water.
Bring them to a boil and immediately shut off the heat. This breaks the capsules around the beans and allows the gas-causing sugars, stachyose and raffinose, to escape into the water.
Then add 2 tablespoons of baking soda (the sugars are more soluble in alkaline water), and let the beans sit overnight. The next morning, drain the water and wash the beans thoroughly. Now they are ready to be cooked and eaten.
Dr. Mirkin is a practicing physician in Silver Spring specializing in sports medicine and nutrition.