Most runners spend hours stretching their leg muscles. A recent report in the American Journal of Sports Medicine shows that stretching does not prevent running injuries, nor does cooling down prevent next-day muscle soreness. The only way to prevent injuries is to stop exercising when you feel pain and to avoid stressing the same muscle groups more often than every other day.
The myth about stretching preventing injuries comes from the fact that every time you exercise, your muscle fibers are torn and frayed, and when they heal, they shorten. However, there are no controlled studies to show that short, tight muscles are more likely to be injured or that stretching prevents injuries.
However, stretching can help to make you a better athlete because longer muscles generate more force about a joint and help you to run faster, throw farther, lift more and stretch farther.
Several studies show that warming up can help to prevent injuries because a resting muscle has a temperature of only 96 or 97 degrees. Warming up by exercising slowly before exercising more vigorously raises a muscle's temperature and makes it more pliable.
However, cooling down does not prevent the muscle soreness that you feel on the day after exercising.
Exercising slowly after exercising more vigorously helps to clear lactic acid from muscles, but an accumulation of lactic acid does not cause next-day muscle soreness. Muscle soreness is caused by muscle damage and is prevented by slowing down when your muscles start to burn and hurt.
Q: Do you have any new ideas to help me persuade my former-athlete husband that exercise will make him feel younger?
A: Tell him that all of the tests that are used to measure aging actually measure physical fitness. Scientists measure aging with a test called VO2-max, your maximal ability to take in and use oxygen.
Recent studies from Ball State University, Cortland State, Washington University in St. Louis and Mt. Sinai Medical Center in Milwaukee show that intense exercise maintains fitness.
People who do not exercise lose 15 percent of their fitness per decade, and those who exercise at low intensity lose 9 percent. But those who exercise intensely barely lose any fitness at all.
At age 50, former Olympian Fred Wilt was able to run 2 miles in less than 10 minutes. His routine was to run just five to seven miles a week, alternating almost flat-out 200-meter runs with jogging until recovery. His five to seven miles a week don't even compare to a world-class runner's regimen of more than 100 miles a week.
With increased intensity comes an increased risk of injury. So, before your husband starts an exercise program, check with your doctor. Realize that older people can't train intensely very often. If you go out and run alternate fast and slow 200-meter runs on one day, you may have to wait from two to 10 days before you can run fast again.
The best way to maintain fitness with aging is to exercise very intensely in one sport on one day and then rest for the next few days, try another sport before you try to exercise intensely again in the same sport.
Q: Are estrogen and testosterone patches better than pills?
A: Taking the female hormone, estrogen, by mouth helps to prevent heart attacks, while taking it by patch does not.
When a woman takes estrogen pills, they pass from the intestines into the bloodstream. All blood from the intestines passes directly to the liver, which removes estrogen on the first pass.
Estrogen then causes the liver to make increased amounts of the good HDL cholesterol that prevents heart attacks. When a woman uses an estrogen patch, the estrogen goes into the bloodstream where it is picked up by muscles and other tissues and reaches the liver only in extremely low concentrations.
A similar principle applies to the new testosterone patches that will be available soon for men. A man's blood level of testosterone drops more than 40 percent from age 50 to 70.
However, when a man takes testosterone pills, the testosterone goes from his intestines into the liver where it lowers the good HDL cholesterol and increase a man's chances of getting a heart attack.
When he takes it by patch, the testosterone does not go to the liver and it may even raise blood levels of the good HDL and lower blood levels of the bad LDL cholesterol.
The major unanswered question is whether testosterone patches will cause an undiagnosed pre-existing prostate cancer to spread through the body.
Dr. Mirkin is a practicing physician in Silver Spring specializing in sports medicine and nutrition.