Newsgroups: sci.space.shuttle
From: henry@spsystems.net (Henry Spencer)
Subject: Re: Question: Fluid Loading??
Date: Wed, 23 Feb 2000 15:03:11 GMT

In article <jvk7bs8r6g8eaoaos8hc28je7an6kd5hpr@4ax.com>,
George R. Kasica  <georgek@netwrx1.com> wrote:
>...crew to "delay fluid loading".....I give up....what fluid(s) and
>load to where....I'mn taking a GUESS from a medical perspective that
>it may have to do with them consuming something on ther order of water
>to raise the fluid load in the body and hence help preserve blood
>pressure stability on entry and landing as they return to 1G?

Correct.  There is substantial reduction of blood volume in the first
couple of days of free fall, because gravity is no longer pulling blood
down into torso and legs, and the body's "too much water, get rid of some"
sensors are in the head.  The fluid shift reverses on landing, causing (or
at least aggravating) problems like lightheadedness when standing up, and
so it's worth trying to load up on fluids just before descent.

(The Russians have also experimented with the reverse, taking a diuretic
before launch to reduce fluid volume and thus reduce the side effects of
the upward fluid shift.)
--
Computer disaster in February?  Oh, you |  Henry Spencer   henry@spsystems.net
must mean the release of Windows 2000.  |      (aka henry@zoo.toronto.edu)

Newsgroups: sci.space.shuttle
From: henry@spsystems.net (Henry Spencer)
Subject: Re: Question: Fluid Loading??
Date: Thu, 24 Feb 2000 03:52:07 GMT

In article <891ols.3vvhpf1.0@mm.invalid.de>,
Markus Mehring  <m.m@gmx.net> wrote:
>>...and the body's "too much water, get rid of some"
>>sensors are in the head.
>
>Huh? In the head? To the best of my knowledge, those sensors are in the
>chest, near the heart.

Hmm, you may be right -- my memory of this isn't as specific as I thought.
--
Computer disaster in February?  Oh, you |  Henry Spencer   henry@spsystems.net
must mean the release of Windows 2000.  |      (aka henry@zoo.toronto.edu)

Newsgroups: sci.space.shuttle
From: henry@spsystems.net (Henry Spencer)
Subject: Re: Microgravity Exercise Programs
Date: Wed, 8 Jul 1998 17:02:18 GMT

In article <0pcrKBG00WB54g6VR4@andrew.cmu.edu>,
Jacob McGuire  <mcguire+@andrew.cmu.edu> wrote:
>>The main objective of space exercise is maintaining cardiovascular
>>fitness, not increasing muscle mass or building strength.
>
>  I thought that the big problem in microgravity was maintaining
>lower-body and back strength, so that you could still move around when
>you got back to earth.  Of course, this comes from descriptions of
>astronauts being unable to move when they get back to earth, which I
>guess isn't very specific.

Not very, no.  The dominant problem, as I understand it, has been
orthostatic intolerance, i.e. you faint if you try to stand up, because
your heart isn't up to maintaining blood supply to the head in 1G.  So
cardiovascular conditioning is the big issue.  This problem seems to be
under control now -- Valery Polyakov walked off the airplane unassisted at
Star City in 1995, after 14 months on Mir.
--
Being the last man on the Moon is a |  Henry Spencer   henry@spsystems.net
very dubious honor. -- Gene Cernan  |      (aka henry@zoo.toronto.edu)