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Vernon Mcdonald
06-23-1994, 12:32 AM
Netters,
I posted this request a week ago and as promised here are the
responses. Thanks for your help.

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I have a colleague here at JSC who is studying the effects of physical
activity on the development of decompression sickness (the bends). The
development of "bubbles" in the joint cavities is apparently influenced by
certain types of physical activity. For example those people who engaged
in locomotion or push-up's were more likely to develop the bends during
decompression than those who engaged in activities such as hand ergometer
exercise, turning a torque wrench, or a form of rowing (upper limbs only).
My colleague is trying to identify dimensions that separate these two
groups [locomotion or push-up's] vs. [hand ergometer exercise, turning a
torque wrench, or a form of rowing] relative to musculoskeletal dynamics.

I have asked him for details on the kinetics involved in each of the upper
body activities he used since there could be distinct power requirements.
However, it occurred to me that perhaps one difference is the necessity for
the maintenance of joint stability. An analogy is performance of the bench
press using a machine vs performance of the bench press using free weights.
In locomotion

Consequently I have two questions for this forum:

1) Has there been any research studying muscular activation patterns and
the role of joint "stabilizers" in various activities?

2) Do you have any other suggestions as to dimensions that separate these
two groups of physical activity.

>Date: Tue, 14 Jun 1994 10:54:32 +1000
>From: John Baker (Tel \(06\) 252-1558 )
>To: vmcdonald@plato.jsc.nasa.gov
>Subject: RE: DECOMPRESSION BUBBLES
>
> 14/6/94
>
> Dear Vernon,
>
> In reply to your request on Biomch-l regarding types of physical
> activity and decompression sickness have you considered the type
> of muscular contraction involved? That is the hand ergometer
> exercise, turning the torque wrench and the rowing would
> primarily involve concentric contractions while for the push-ups
> there would be eccentric and concentric activity of the relevant
> muscle groups. As the eccentric contractions are more likely to
> cause structural damage there may be a relationship between
> developing the bends and the corresponding structural damage
> caused by the eccentric contractions.
>
> Yours sincerely,
>
> John Baker
> Australian Institute of Sport
> E-mail: John.Baker@AUSPORT.TELEMEMO.AU
>


>Date: 17 Jun 94 00:58:40 EDT
>From: "Martyn R. Shorten, Ph.D."
>To: Vernon McDonald
>Subject: decompression bubbles
>
>I'm not an expert on joint mechanics but ...
>
>The activities appear to be separated by the way the joints are loaded in
>compression
> or tension during the exercise. During locomotion and push ups, the joints
>are loaded in compression.
>During torque wrenching and rowing (arms only) this is not the case.
>
> The physiological difference would derive from the fact that fluid is
>squeezed out of
> articular cartilage under compression. Post exercise, the cartilage
>reabsorbs fluid. Perhaps the joints
> with squeezed or recovering cartilage are somehow more susceptible to
>decompression.
>
>No evidence, no references, just an idea. A joint or cartilage expert would
>tell you if it is crazy or not.
>

>Date: Tue, 14 Jun 94 15:19:22 PDT
>From: Jacklyn Heino
>To: Vernon McDonald
>Subject: Re: decompression bubbles
>
>Vernon
> On first thought, I cannot see that the amount of joint stabilization
>will be the distinguishing factor. Both upper extremity rowing and torque
>wrench motions require high amounts of joint stabilization. Have you
>considered the muscle masses involved? Upper versus lower extremity?
>Perhaps the lower extremity involvement affects the bends somehow??
>Interesting question!
>Jacki Heino P.T.
>


__________________________________________________ ______________
Vernon McDonald | Motor Performance Lab.
KRUG Life Sciences, | NASA/Johnson Space Center
TEL: (713)-244-6349 |
FAX: (713)-483-3058 | vmcdonald@plato.jsc.nasa.gov
__________________________________________________ ______________