With Mars And The Moon In View, Human Physiology Study Shows 6Degrees Of Decline Is The Ticket To Ride (Forwarded)

American Physiological Society
Bethesda, Maryland

Contact:
Mayer Resnick, Communications Officer
Office: 301-634-7209

EMBARGOED FOR PUBLICATION: TUESDAY, MARCH 28, 2006

With Mars And The Moon In View, Human Physiology Study Shows 6 Degrees Of
Decline Is The Ticket To Ride

Human ability to exercise quickly drops over 10% in space and bedrest,
study shows, confirming that head-down approach really works

Results bode well for astronaut safety, benefits to aged and bed-ridden

BETHESDA, MD -- With President Bush talking up trips to the moon and Mars,
and a new satellite circling the red planet, ever wonder what it feels
like in space? The expensive way to find out is to hitch a ride on a
parabolic aircraft trip, where you may get up to 90 "weightless" sessions
of about 20 seconds each.

But if you want to find out how space flight actually affects the body,
just lie down and recline your head at a 6-degree angle below your feet
for a few days.

A study in the March issue of the Journal of Applied Physiology shows for
the first time that a person at "reclining bedrest" reacts almost exactly
the way an astronaut's body adapts to space.

According to lead author Todd Trappe: "Over 17 days in space, like in
bedrest, we found that our ability to work or exercise began to fall
almost immediately. It reached a low point at 13 days because the
cardiorespiratory "engine" lost the ability to provide the body with
oxygen it needs."

"This has important implications for aiding earthbound elderly, bedridden,
and other individuals subjected to periods of inactivity, and also for
helping to ensure the ability of our space travelers to operate as far out
as Mars," Trappe added.

The paper, "Cardiorespiratory responses to physical work during and
following 17 days of bedrest and spaceflight," appears in the March issue
of the Journal of Applied Physiology (JAP), published by the American
Physiological Society. Research was by Todd Trappe, Scott Trappe, Gary Lee
and David Costill of Ball State University, Indiana, and Jeffrey Widrick
and Robert Fitts of Marquette University, Wisconsin.

Soviet-U.S. interaction set 6-degree standard, but Trappe et al. showed it
works

Since the early space flights in the 1960s, researchers in the U.S. and
Soviet Union knew they needed an earth-bound way to study the physiology
of space flight (SF). Early experiments used "chair rest," since space
explorers were strapped in a chair.

"But once men started coming back from space it was obvious the
cardiovascular system was significantly impacted by the microgravity
environment, and physiologists realized they needed a way to model this in
the gravitational environment on Earth," explained Todd Trappe, lead
author of the article in the March issue of JAP.

Trappe and his colleagues performed "side-by-side" studies comparing
cardiorespiratory responses to exercise and work by four astronauts on the
17-day STS-78 (Life and Microgravity Spacelab Mission) and eight
earthbound bedrest subjects who mimicked the astronauts' schedules and
most of their activities.

The so-called "head-down minus 6 degree bedrest" paradigm resulted from
early interactions between the Soviet and U.S. researchers and doctors
that considered a large range of angles that would mimic the
cardiovascular effects of microgravity experienced by humans in space.
However, "until our parallel studies on the STS-78 and at bedrest (BR), it
was never specifically tested," Trappe noted.

A "main finding from this study highlights the adequacy of (minus
6-degree) BR as an analog for space flight," the paper stated.
Furthermore, the findings showed that "minus-6-degree BR is an appropriate
simulation of in-flight and postflight physiological responses to
exercise. This is evidenced by the fact that the direction, magnitude, and
time course of the changes in the cardiorespiratory responses to exercise
were similar between BR and SF."

Parallel swift, steep declines in SF and BR indicate validity of mutual
applications

Specifically, the paper reported: "Exposure to and recovery from SF and BR
induced similar cardiorespiratory responses to exercise (either) on a
semi-recumbent (SF) or supine (BR) cycle ergometer during submaximal and
maximal exercise." Not only did the experiments find "that maximal
exercise capacity is compromised during and following SF exposure," but
the paper reported that the "time course of changes in cardiorespiratory
responses was consistent between SF and BR."

For instance, the decline in cardiorespiratory responses on day 13 was
biggest for both SF and BR in three parameters:

* oxygen consumption maximal exercise: SF minus 11% and bedrest minus 9%,

* change in oxygen pulse maximal exercise: SF minus 18%, BR minus 12%

* change in oxygen pulse submaximal exercise SF minus 11%, BR minus 12%

The recovery of main variables that describe the cardiorespiratory system
were also very similar between the SF and BR, suggesting that programs
designed from BR to help astronauts once they arrive at the moon or Mars
should be effective.

Demonstration of body's quick physiological response to environmental
change

"In a way, the general changes that the body undergoes is somewhat
simplistic," Trappe said. "Your body literally changes its physiology to
what is demanded of it, and in microgravity and during bedrest, if you are
not exercising there is not much physical demand placed on the body due to
the lack of gravity. Our study adds to the relatively small pool of
space-based physiological data from earlier studies that have shown how
quickly the muscles, bones, and cardiorespiratory system change when they
are not needed or used."

Next steps

According to Trappe, the import of the study isn't just that the SF-BR
paradigm is valid, but it holds out the hope that health-care approaches
based on SF and BR could be translated into the other arena. He gave
several examples:

* "Need to determine the minimum amount of exercise necessary to maintain
astronauts' bone and muscle mass, as well as the cardiorespiratory
capacity to support the physical work that will be required of astronauts
when they travel to the moon or Mars.

* "Once the level above is determined, it could have important
implications to amount of exercise that elderly or bedridden persons might
need to get or remain healthy.

* "Based on what we learn from the three- to six-month stays on the
International Space Station, we might be able to adapt physical, drug or
other types of therapies to help people recover from medical conditions
that require inactivity or immobility," Trappe said.

Editor's note: The types of "next steps" research outlined by Trappe are
termed "countermeasures research" by NASA. The Federation of American
Societies of Experimental Biology (FASEB), of which the American
Physiological Society is a member, has published NASA commentary in its
recommendations on the fiscal 2007 Federal Budget.

FASEB's NASA report, calling for restoration of basic life science
spending and increased spending for countermeasures research and
investigator-initiated, peer review life sciences research can be found at
http://opa.faseb.org/pdf/funding_report_NASA.pdf

Source and funding

The paper, "Cardiorespiratory responses to physical work during and
following 17 days of bedrest and spaceflight," appears in the March issue
of the Journal of Applied Physiology, published by the American
Physiological Society. Research was by Todd Trappe, Scott Trappe, Gary Lee
and David Costill of the Human Performance Laboratory, Ball State
University, Muncie, Indiana, and Jeffrey Widrick and Robert Fitts,
Department of Biology, Marquette University, Milwaukee, Wisconsin.

Research was supported by the National Aeronautics and Space
Administration/NASA (Fitts).

Editor's note: The media may obtain a copy of Trappe et al. by contacting
Mayer Resnick, American Physiological Society, 301.634.7209.

* * *

Space research for high school students and teachers at Experimental
Biology 2006

"What price a Martian? Human limits to exploring the red planet," a
presentation by James A. Pawelczyk, associate professor of kinesiology and
physiology at Pennsylvania State University and specialist NASA astronaut,
launches the APS Education Day for High School students and teachers,
Monday, April 3 in San Francisco.

Todd Trappe, Pawelczyk and others will participate in a physiology careers
forum. After lunch, students and teachers will visit EB sessions and then
participate in a series of "inquiry-based" hands-on experiments on
exercise and the cardiovascular system developed by the APS Education
Committee and Education Office.

Editor's note: The full program high school program is available at
http://www.the-aps.org/education/EB/...orkshop06.html

* * *

Latest space-related research to be presented at EB poster sessions

Pawelczyk, various members of the Trappe et al. team, as well as other
researchers are presenting more than 20 papers in the American
Physiological Society session (#765) on "gravitation and space" physiology
on Tuesday April 4 at the Moscone Convention Center Exhibit Hall in San
Francisco.

Separate news releases will be issued closer to Experimental Biology's
opening on April 1 on the APS Press Room "conferences" hotlink:
http://www.the-aps.org/press/

The complete, fully searchable program for EB is available at

http://www.eb2006-online.com/welcome...af5e0239 a3bf

* * *

The American Physiological Society was founded in 1887 to foster basic and
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APS provides a wide range of research, educational and career support and
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