Found this while rummaging around.  It is sort of applicable to the
exercise question, but only gives a partial picture of the whole
subject.  I suspect the reason exercise extended the average life of
unrestricted animals is that it helped to prevent glycolization from
the excess glucose floating around in their systems, but note that
in restricted animals it clearly shortened life:

>Date:	16 May 1996 06:25:16 GMT
>From:	[log in to unmask] (Doug Skrecky)
>Newsgroups:	sci.life-extension
>Subject:	Exercise & Calories

>From [log in to unmask] Wed May 15 23:15:14 1996
>Date: Thu, 25 Apr 1996 21:17:09 -0700 (PDT)
>From: Doug Skrecky <[log in to unmask]>
>To: [log in to unmask]
>Cc: [log in to unmask]
>Subject: Re: Low calorie or low weight?

>On Thu, 25 Apr 1996, Ian Eiloart wrote:
>> My question is this. Are there any animal experiments that
> prove that body weight is important variable here?
>> Humans can adjust their weight by diet or exercise. Are
> there animal experiments that test this variable?
>> Can I still eat a lot (well a reasonable amount) if I get
> my weight down by exercising, and still hope to live longer?

>Unfortunately exercise does not possess the age retarding
> effect of caloric restriction. Rats that lose weight by exercising do
> not live as long as those on a diet. The following chart derived from
> Journal of Applied Physiology 70(4):1529-1535 1991 tells the tale:

>   GROUP         AVERAGE   OLDEST
> OF RATS         LIFESPAN  LIFESPAN
>A: controls          875   1200
>B: exercised         978   1208
>C: 30% restricted   1056   1322 (same weight as B)
>D: exercised &       995   1328
>   30% restricted
>E: 46% restricted   1088   1341 (same weight as D)

>As can be seen exercising can even reduce the average (but
> not maximum) lifespan of restricted Long Evans Rats.

--Doug Schwartz
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