Dear Group:

If you need any more inspiration to get out there and walk, here's
some more information about why exercise is important as we age:

Aging muscles become hard of hearing
But regular exercise can help speed up response time



Updated: 1:19 p.m. MT March 20, 2007
As people age, neurons have to yell louder at the body's muscles to
whip them into action, according to a new study, but exercise could
reverse the aging effect.

Researchers examined the relationship between neuron activity and
corresponding muscle force for 23 subjects between the ages of 18
and 88. They found a diminished ability of the muscles to respond to
the commands of neurons amongst the older participants.

Specifically, the researchers looked at the dorsal interosseous
muscle, situated between the index finger and thumb. This muscle is
activated by 120 individual neurons. Each subject had a small needle-
like electrode inserted into their index finger. The electrode was
hooked up to a computer which recorded the electrical impulses as
they traveled from the neurons to the muscle fibers.


The participants were asked to use that finger to follow the outline
of a wavy line with peaks and valleys on a computer screen.

"More force — which this indicated by a corresponding higher firing
rate of neurons — is exerted just before you begin the upturn toward
one peak and then it eases off again in the downturn toward a
valley," said Christopher Knight, a researcher from the University
of Delaware.

The tests showed neuron firing rates and muscle responsiveness were
lower in older participants than the younger subjects.

"The repeated contraction of muscles is essential to movements such
as walking," Knight said. "However, our muscles have a reduced
capacity to contract or 'twitch' as we grow older. We lose fast-
twitch muscle fibers as we age."

This type of reduced neuron activity, Knight said, could be improved
however with exercising.

"After power training with weights, we see an increase in firing
rates," Knight said. "For safety, we're commonly advised to do
things slowly when exercising, but it's important to also do some
fast exercises. You need a fast movement to prevent a fall. Even in
the frail elderly, it is possible to use exercise bands for manual
resistance to improve the speed of movement."

The study was detailed in the January issue of the Journal of
Applied Physiology.