Greater Endurance with Aging According to Dr. Gabe Mirkin

In his January 18 ezine, Dr.Mirkin says:

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.

Dr.Mirkin's reports and opinions are for information only,
and are not intended to diagnose or prescribe. For your specific
diagnosis and treatment,consult your doctor or health care
provider. For more information
visit http://www.drmirkin.com