Greater Endurance With Age...
And lots of other good stuff.
Though long, this is too good not to share.
Because it has everything in it (recipes, training, physiology) I didn't quite know where to put it.
Dr. Gabe Mirkin's Fitness and Health E-Zine
January 18, 2009
Greater Endurance with Aging
I'm 74 years old and ride my bicycle more than 200 miles
per week, often in pace lines with younger riders. I have noticed
that younger riders can easily pull away from me in short bursts,
but I keep coming back on them and seem to be better able to
keep up with their accelerations as the ride progresses.
The latest issue of Exercise and Sports Sciences Reviews
(January 2009) reviews the entire world's literature to show that
endurance improves as you age. Wow!
The maximal muscle contraction force occurs when you do
a single muscle contraction with all your might. Even though older
people are not as strong as younger ones, many studies show that
they can retain maximal force after many contractions far longer
than younger people can.
Here's the theory and evidence to explain why aging
improves endurance. Muscles are made up of millions of
individual fibers just as a rope is made up of many different
threads. Each muscle fiber is enervated by a single nerve. As you
age, you lose nerves throughout your body and when you lose the
nerve that enervates a specific fiber, you also lose that muscle
fiber.
Muscle fibers are classified as type I endurance fibers
and type II strength and speed fibers. With aging, you lose far more
nerves that enervate the strength and speed fibers than those that
enervate the endurance ones. So, with aging, you lose strength but
you retain a greater proportion of endurance fibers.
Muscle fatigue comes from the accumulation of waste
products that occurs while food is converted to energy to power
your muscles. Scientists can measure fatigue by measuring the
accumulation of acid (H+), Phosphate (Pi) and protonated
phosphate (H2PO4) in muscle. With the same percentage of their
maximal muscle force, older people accumulate far lower levels of
these end products than younger people do. Therefore even
though older people are weaker, they can maintain their forceful
contractions far longer than younger people can and they have
greater endurance. This exciting recent data will encourage me to
train even harder.
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Reports from DrMirkin.com
Weight loss with metformin
http://www.drmirkin.com/nutrition/N117.htm
Protein requirements
http://www.drmirkin.com/nutrition/9085.html
Lactose intolerance
http://www.drmirkin.com/nutrition/N194.html
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Dear Dr. Mirkin: I'm an avid runner who gets severe leg cramps;
could they be caused by an over-the-counter supplement that
contains beta sitosterol?
Beta sitosterol is a plant cholesterol that blocks the
absorption of animal cholesterol in your intestines. It's unlikely
that these supplements would cause your leg cramps. Low salt levels
are a far more common cause of cramps in exercisers. When you
exercise intensely, you lose tremendous amounts of salt in your
sweat. Go for a long run of at least ten miles. On the next morning
have your doctor draw your blood sodium level. If it is below 130,
you need more salt.
Try adding more salt to your food and eat salted peanuts
or other salty snacks frequently during your rides. Salt may
contribute to high blood pressure in non-exercisers, but it rarely
causes high blood pressure in athletes. If you are concerned about
the effect of added salt on your blood pressure, get an
inexpensive wrist blood pressure cuff at your local drug store and
keep a log.
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Dear Dr. Mirkin: Should I exercise when I have a cold or a fever?
Exercise may actually be beneficial when you have a cold.
However, it's probably better to stop exercising altogether if you
have a fever with aching muscles. When you exercise, your heart
has to pump blood to your muscles to supply them with oxygen. It
also must pump blood from your muscles to your skin where the
heat is dissipated. When you have a fever, your heart has to work
harder to get rid of extra heat.
You risk injury if you exercise when your muscles hurt at
rest. When muscles are damaged, they release enzymes from their
cells into the bloodstream and they fill with blood from broken
blood vessels. One study reported markedly increased muscle
damage during relatively minor exercise during an infection, with
blood tests showing increases in muscle enzymes and ultrasound
tests demonstrating hemorrhage into the muscles. You will not
lose much conditioning if you take off a few days.
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Recipe of the Week:
Spanish Rice
http://www.drmirkin.com/recipes/spanish.html
You'll find lots of recipes and helpful tips in
The Good Food Book - FREE at
http://www.drmirkin.com/goodfood/index.html
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