CR + ON + Exercise ......... Was Re: 2 CR videos

[Guest guest]

Hi folks:

Once again Al hits the bull's eye, at least from my point of view,

with this post. And not only because of the videos.

For what it is worth, here is what I think I got out of the Holloszy

paper Al linked.

I had seen this paper previously - it is dated 1997 - but I got a lot

more out of it this time than the last time I read it. This was

largely, I think, because I am searching for different information

now than I was years ago. Then, given very limited knowledge of CR,

I was anxious to find information that justified CR in principle, and

was looking for material that would help me decide the degree of CR I

should pursue. (Also a factor, perhaps, was that I had, and still

have, difficulty getting my brain around the wording used in the

abstract of this paper. I had to read each section five times to be

reasonably sure I grasped what it was it was trying to say!)

Now I am interested in different issues. Here are a few of what I

see as some of the more important points of this paper:

They had four groups of rats. A) Runners on 8%* CR; Sedentary on

8%* CR; C) Runners on 30%* CR; D) Sedentary on 47%* CR (the level

that turned out to be the intake that resulted in body weights equal

to the exercisers of group C). For all groups CR was initiated in

these Long- rats at three months of age. (Can anyone help

clarify what the comparable age would be for humans? Is it after the

attainment of full growth? I have ascertained that it *is* after

puberty for these rats.)

* NOTE: Percentage CR is defined as the amount consumed relative to

ad lib intake.

When I saw the above list of groups I was very disappointed they did

not have a fifth group of sedentary rats on 30% CR, so that we could

also compare the survival curves of sedentary and exercising groups

with identical restricted caloric intakes. As it turned out I didn't

need to be concerned.

Here are some quotes from the paper that seem relevant to me, many of

which will be no surprise to those generally familiar with CR

literature:

" Our research on rats is done with the assumption that it has

relevance to humans. "

" ........ [a] mild [8%] degree of food restriction ......... does

not affect longevity of sedentary rats. "

" [30%] Food restriction increased both the average and maximal life

spans of sedentary rats. "

" Wheel running alone improved the average survival of the [8% CR]

group A rats, but did not result in an extension of maximal life

span. "

" [30%] Food restriction [plus running] caused a significant increase

in maximal longevity. "

" The [30%] food-restricted runners in group C .......... had a

survival curve that was virtually identical to that of the [47%

restricted] sedentary control animals. " [but unfortunately the

different degrees of restriction make this a not entirely fair

comparison of restricted runners with restricted sedentaries.]

" The [30%] food-restricted runners in group C had a significantly

longer average survival than the [8% restricted] runners in group A. "

But for me the most notable aspect of this paper, which had gone over

my head previously (and which I do not remember seeing discussed

here), relates to a comparison of the survival curve of CR+exercise

with that of CR alone. Here are some, in some cases poorly worded

imo, quotes about this:

" A decrease in the availability of energy for growth and cell

proliferation that induces an increase in maximal longevity in

sedentary rats only results in an improvement in average survival,

with no extension of maximal life span, when caused by

exercise. " ...... and:

" Our previous study included both ~30% and ~50% food-restricted

sedentary groups, and their survival times were also not

statistically significantly different. "

MY CONCLUSION: If sedentary 30% restricted animals experience

survival curves similar to 50% restricted sedentaries; and 47% CR

sedentaries experience survival similar to the 30% CR runners (see

above); then it would appear the inescapable conclusion must be that:

**** exercise does not help rectangularize the survival curve of

animals on CR **** .....

...... let alone further extend maximum lifespan.

This has been briefly discussed here previously. An important

logical conclusion that it seems to me must be drawn from this paper

is that the rectangularization benefits observed in exercising, fully

fed, animals only solves the kinds of problems that are already

solved by CRON. So there is no additional benefit to be derived from

exercise for an animal already experiencing the benefits of CRON -

since CRON itself has already provided those benefits. Indeed, in

the paper this is explicitly stated:

" The beneficial effects of food restriction and exercise on survival

are not additive or synergistic. "

If anyone knows of any studies where it was found that, contrary to

what was found in this study, exercise did help rectangularize the

survival curve in ***CRON*** animals, PLEASE post it. TIA. We all

recognize there is little that is known for absolutely certain about

these things - beyond the fact that CRON extends average and maximum

lifespan.

Granted, rats are not humans, but remember the: " Our research on

rats is done with the assumption that it has relevance to humans " .

Granted also, future studies may arrive at different conclusions from

this one. But one unavoidable conclusion to be drawn from this paper

seems to be that if these results are applicable to humans, those

pursuing CRON will derive no additional longevity benefit from

exercise beyond the rather minimal threshold level we all agree is

necessary to maintain health (bed-ridden little old ladies generally

do not survive for long, etc..) such as that expended by a sedentary

rat while ambling around a cage not equipped with exercise facilities.

In one sense this item was big news to me, as I had not previously

been aware that there were any papers addressing the issue. But on

another level it fits in very nicely with the findings of the New

England Centenarian Study. It found no consistent patterns in the

exercise habits of their centenarian subjects. Some had exercised

extensively. Many, not at all.

Alternative perspectives, backed by supporting evidence, are, of

course, as always, more than welcome. And it is acknowledged that

there is presumably an exception to be made regarding the

desirability of types of exercise appropriate for prevention of

osteoporosis.

Rodney.

=============================================

>

> Hi All,

>

> Below, are two CR videos. I also include the reference in the

first video (presented at the symposium) of the free-full text paper

by Holloszy JO.

>

> The data on the http://en.wikipedia.org/wiki/TUNEL_assay of CRed

aptosis in later life appeared to be new and impressive.

>

> Is Caloric Restriction the Key to a Longer and Healthier Life?

(Luigi Fontana)

> http://www.edmontonagingsymposium.com/files/eas/presentations/08-

Luigi_Fontana.wmv

> http://tinyurl.com/2mrl3y

>

> Holloszy JO.

> Mortality rate and longevity of food-restricted exercising male

rats: a reevaluation.

> J Appl Physiol. 1997 Feb;82(2):399-403.

> PMID: 9049716 http://tinyurl.com/qgxe3

>

> Mechanisms by which Caloric Restriction Better Preserves Skeletal

Muscle Mass & Function with Aging

> http://www.edmontonagingsymposium.com/files/eas/presentations/07-

Russ_Hepple.wmv

> http://tinyurl.com/373wcj

>

> -- Al Pater, PhD; email: Alpater@...