March 13, 2005
Sugar Before Exercise
For more than 20 years, athletes were told to avoid
sugary meals within three hours of a competition. In 1977,
researchers found that eating sugar within three hours of
exercising caused blood sugar levels to shoot sky high and then
to fall to low levels. Eating sugar causes blood sugar levels to
rise. Your pancreas responds by releasing large amounts of
insulin which remain in your bloodstream when you start to
exercise. The insulin already in your bloodstream plus muscles
drawing large amounts of sugar from your bloodstream can cause
your blood sugar to drop to very low levels. Since 99 percent of
the energy for your brain comes from blood sugar, it was felt that
your brain would suffer from lack of an energy source and you
would feel terribly tired and pass out. Low blood sugar levels
cause tiredness and passing out, but athletes are able to tolerate
extremely low blood sugar levels during competitions without
even slowing down.
More recent research has shown that eating sugar prior
to competition can enhance performance. The extra calories are
there to continue fueling your muscles. You should eat one to
five hours prior to competition and you can eat sugary foods.
Your only concern is that your stomach should be relatively
empty when you start to exercise, so some athletes avoid fatty
foods that stay in the stomach for a longer time. Easily-digestible
pre-event foods include fruits and fruit juices, breakfast cereals
with skim milk, muffins, bagels and so forth.
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Dear Dr. Mirkin: Is it safe to use a hot tub in a hotel or health
club?
It’s extremely unlikely that you will pick up a viral
infection in the hot tub, but you can get folliculitis, a bacterial
infection. Viruses such as herpes are killed almost immediately
in chlorinated water. The herpes virus can survive for up to four
or five hours on the edge or seats that are not underwater.
However, even if you sit on the same spot that a person with
active herpetic blisters has just left, you probably wouldn't be
infected. To acquire herpes, you need to allow the virus to pass
through broken skin.
Hot tubs that have not been adequately chlorinated can
give you folliculitis, a condition that causes severe itching and red
bumps on the skin. It can be cured with antibiotics, but often
goes away by itself without treatment. If you use public hot tubs,
pools and whirlpools, sit on a towel on the side of the tub or pool,
and shower immediately after you leave the water. If you start to
itch, check with your doctor.
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Dear Dr. Mirkin: What’s the best exercise to strengthen my heart
and give me large muscles?
I can’t think of any single exercise that will do all that. To
strengthen your heart muscle, you have to exercise vigorously
enough to make your heart pump more blood. This means your
exercise must speed up your heart rate and keep it elevated for a
while. The formula for heart-lung fitness is to exercise vigorously
enough to raise your heart rate at least 20 beats a minute above
your resting rate, and try to work up to 30 minutes, 3 times a
week. If you can't exercise continuously for thirty minutes,
exercise, stop when you feel tired, and repeat the cycle.
To strengthen your skeletal muscles, you have to
exercise against increasing resistance, such as lifting heavy
weights or pushing against special strength-training machines.
The greater the resistance without causing injury, the greater the
gain in strength. However, when you exercise against resistance,
your muscles fatigue very rapidly. If you exercise against
resistance for more than 50 continuous seconds, you increase
your risk of tearing your muscles. You cannot maintain resistance
that is needed to increase skeletal muscle strength significantly
for the longer periods needed for heart strength.
You could pick a sport such as cycling for heart muscle
fitness, and then climb lots of steep hills to provide resistance to
strengthen your muscles. However, cycling stresses primarily the
upper legs, so you would still need another activity to strengthen
your other skeletal muscles. It’s better to pick a sport you enjoy
to strengthen your heart, such as running, fast walking,
swimming, cycling, dancing or any other continuous exercise. To
strengthen your skeletal muscles, use weights or special
strength-training machines. A good program would include
cycling or running on Mondays, Wednesdays and Fridays and
using strength machines on Tuesdays and Thursdays.
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This week we have three tasty RECIPES contributed by readers:
Michael’s Eggplant Sauce for Whole Grains
Ruth’s Quickest Rice Pudding Yet
Alan’s Faux Mueslix
If you have a healthful recipe you’d like to share,
please send it to info@drmirkin.com
List of Diana's Healthful Recipes