Re: [RC] Bioengineered Endurance Athletes? - Jon . Linderman
As one of "them" who has done work witrh muscle fiber type changes for most
of my career let me say that recent publications of changes in muscle fiber
types are really nothing new. We knew since the 70's that rodent muscle
could undergo dramatic changes from fast to slow with various interventions
that caused the muscle to be chronically recruited. These interventions
showed us the envelope to which a muscle can be changed. A practical
application of this in the training of mammals: dogs, rats, and humans is
that prolonged periods of low intensity activity alters the fiber
characterisitics of the muscle to be more slow twitch.......we have called
this LSD long slow distance training.
It should be cautioned that slow twitch refers to the contraction speed of
the muscle, which normally goes hand in hand with the ability to use oxygen
to sustain energy use for prolonged periods of time. However, as we age,
muscle lose high power faster twitch fibers and actually become slow twitch
in nature making us more susceptible to falls etc. However, in this case
the aged slow twitch muscle changes actually results in a decreased ability
to use oxygen and we see reduced work capacity in the elderly. In space
w/the lack of gravity muscles get smaller (atrophy) and actually become
faster twitch which causes them to fatigue more rapidly. In otherwords,
contrary to popular myth we have know for a long time that muscle can
undergo dramtic changes in many environments.
Carl Lewis can not become frank shorter, and vice versa. For those 2 young
to remebver frank shorter won gold and silver in the marathon for the US.
They have a genetic window that endows them with fiber characterisitcs of
their muscles. They can have changes through training, but w/out very
severe, even painful procedures, it is nearly impossible to take a turkey
breast (white; fast twitch muscle) and make it into a turkey leg (dark;
slow twitch muscle). By the way the dark comes from the rino containing
proteins that bind oxygen in the muscle: myoglobin and the cytochromes that
are involved in the use of oxygen. A turkey can walk all day, but can fly
but a few seconds before becoming exhausted. A migratoryt duck or goose
has dark breast meat due to its slow muscle capable of flying form Mexico
to Canada.
By the way the gene for the protein that makes the structure know as
mitochondria, which is where we use oxygen in the muscle cell, is
apparently a maternally linked gene. Thus, great endurance capacity of
muscle comes from mom........not pops!
Jon K. Linderman, Ph.D., FACSM
Assistant Professor of Health and Sport Science
University of Dayton
300 College Park
Dayton, OH 45469-1210
Voice:(937) 229-4207
FAX: (937) 229-4244
jonlinderman@xxxxxxxxxxx
http://www.udayton.edu/~linderma
Truman Prevatt
<tprevatt@mindspring. To: Lynne Glazer <lglazer@xxxxxxxxxxxxxx>
com> cc: ridecamp@xxxxxxxxxxxxx
Sent by: Subject: Re: [RC] Bioengineered Endurance Athletes?
ridecamp-owner@xxxxxx
durance.net
08/19/2002 08:53 AM
Please respond to
tprevatt
There was an article in Scientific American about a year or two ago on
this work and some others. They believe they can change the muscle types
either way. This would produce either super sprinters or super
endurance type muscles. One approach is to alter the genetic composition
of the muscles on a one time basis to change the structure of the muscle
fiblers. The IOC can throw all it's durg testing out the door since
there is nothing to test for.
A brave new world?
Truman
Lynne Glazer wrote:
> Is the horse of the future a transgenic beast? <g>
>
> Scientists create 'endurance' mouse
>
> May lead to wonder drug for distance athletes
> By Kate Tobin
> CNN Sci-Tech
>
> BOSTON, Massachusetts (CNN) --Mighty Mouse lives, and the "new age"
> version is downright buff.
>
> Researchers say they have created a transgenic mouse with muscles like
> a marathoner, capable of enduring rigorous exercise for extended
> periods of time.
>
> While so far the research has only been conducted on mice, scientists
> say they expect the techniques they've developed to treat the mouse
> muscle will also work on humans. Doctors say the discovery may one day
> lead to new treatments for people who are bedridden or have
> degenerative muscle disease, and could prove to be a wonder drug for
> endurance athletes like long distance runners or cross country skiers.
>
> Bruce Spiegelman and colleagues at the Dana-Farber Cancer Institute
> identified a biochemical called PGC-1 that operates as a molecular
> switch, converting so-called "fast-twitch" muscle, which is strong but
> tires quickly, into high-endurance "slow-twitch" muscle.
>
> "PGC-1 appears to be the switch, or a major component of it, that
> enables your body's muscles to adjust to the demands being put on
> them," said Spiegelman. "Understanding how this system works could
> make it possible to develop a drug to manipulate this system."
>
> Muscle is made up of a combination of different types of fibers.
> Endurance athletes train long and hard to build up slow-twitch muscle
> fibers, called Type I fibers, which are long and lean and can keep
> pumping for long periods of aerobic exercise. Sprinters or
> weightlifters, on the other hand, have muscle rich in fast-twitch,
> Type II fibers. These muscles are bulkier and stronger but tire quickly.
>
> Further studies
>
> To create the endurance mouse, Spiegelman's group bioengineered PGC-1
> into mouse muscle tissue. They expected that it would promote the
> development of cellular power plants called mitochondria, which fuel
> the growth and development of slow-twitch muscle fiber. But they were
> surprised to find that PGC-1 appeared to be converting Type II
> fast-twitch fibers into Type I slow-twitch fibers.
>
> The muscle itself actually changed color, taking on a reddish hue
> characteristic of oxygen-rich tissue. Further, in an endurance test at
> a Texas laboratory, the bioengineered muscle turned out to contract
> efficiently two and a half times longer than regular muscle.
>
> Spiegelman cautions that there is still five to 10 years of work to be
> done before PGC-1 based treatments will be available.
>
> The research is published in this week's edition of the journal Nature.
>
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