Dr. Mirkin's E-Zine
November 24, 2002
Walking for Fitness
Walking is a very safe sport because it rarely causes
injuries. Running causes injuries frequently because you take
both feet off the ground at the same time and land with a
tremendous force that can tear muscles and shatter bones. On
the other hand, when you walk, you always keep at least one foot
on the ground and land with minimal foot strike force.
If you want to walk to become fit, you have to move fast.
You should exercise vigorously enough to increase your heart
rate at least 20 beats a minute higher than when you rest. That
means you will be breathing harder and probably perspiring.
There are two ways to increase your walking speed. You can
take longer steps or you can move your feet at a faster rate. To
lengthen your stride, swivel your hips so you reach out further
forward with your feet. This will cause you to twist your body
from side to side, which will tend to make you point your toes
inward when your feet touch the ground. When you point in you
lose distance. Try to point your toes forward with each step.
To move your feet at a faster rate, you have to move
your arms faster. Every time you move one leg forward, you pull
the arm on the same side back and the arm on the other side
moves forward. Your legs will only move as fast as you can
move your arms. Bend your elbows so you can move your arms
faster. The fulcrum of your arm-swing is at your shoulder. The
straighter you keep your elbows, the longer it takes your arms to
swing forward and back. Bending your elbows shortens the
swing and helps you speed up your pace.
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Dear Dr. Mirkin: My aerobics instructor talks a lot about maximum
heart rate. Is it important?
Virtually every student in an exercise class learns that
the fastest rate your heart should beat is determined by the
formula 220 minus your age. But that formula applies only to
out-of-shape people. According to the formula, if you are 40
years old, the fastest your heart can beat is 220 minus 40 or 180.
If you are 20 years old, the fastest your heart can beat is 220
minus 20 or 200 beats a minute. However, fit older athletes can
have the same maximum heart rates as younger people.
The formula depends only on how strong your skeletal
muscles are. Older people who have strong skeletal muscles
can work at very fast heart rates. Your heart rate is driven by
how hard you exercise your muscles. When you start to
exercise, your muscles alternately contract and relax. With each
contraction, the muscles squeeze blood out of the veins near
them. When the muscles relax, the veins near them fill up with
blood. So exercise causes your muscles to pump far more blood
to your heart. The heart responds to the increased return of
blood by beating with more force at a faster rate. The reason
heart rate decreases with aging is because your skeletal muscles
weaken and can't drive your heart as hard as when you were
younger. So if you're fit, forget about the formula. To make your
heart beat faster in a healthful way,00 all you have to do is make
your skeletal muscles stronger.
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Copyright 2002 Sportsmedicine Institute, Inc.
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