RE: Re: Short Bursts of High Intensity Exercise

June 17, 2005

The " short term " high intensity (or Super High Intensity Training) studies show

that we can improve (and/or maintain) aerobic and anerobic fitness without a lot

of time invested. There is some benefit to that for QOL.

However, this type of exercise wont do anything to burn extra calories (for

those who want to) during the exercise time , or increase flexibility or

balance, and you have to be in pretty good shape to begin with to do these.

There is actually a third energy system that comes into play in Super High

Intensiy Training and that is the PCr system or phospho-creatine system (see any

ex phys text book like McCardle, Katch, & Katch) . We only have enough of it

stored in our muscles for short bursts lasting around 10-20 seconds and then we

go to glycogen. It will recycle quickly (as long as the building material is

available) and can be available again in 10 seconds or so. That is why the

famous 4 minute Tabata protocol (references below) was based on performing

eight, 20 second Super High Intensity sprints followed by 10 second rests and

produced very significant improvements in both anerobic and aerobic performance.

Medicine and Science in Sports and Exercise (1996) 28, 1327-1330

Medicine and Science in Sports and Exercise (1997) 29, 390-395

Jeff

________________________________

From: on behalf of Rodney

Sent: Fri 6/17/05 9:15 AM

Subject: [ ] Re: Short Bursts of High Intensity Exercise

Hi JR:

I guess I am looking at this from the point of view that we on CR are

hoping to become elderly people eventually, and to both survive for a

long time being elderly, and be physically capable of doing what we

want to do when we are elderly - including being nimble enough to

avoid falling and breaking bones.

So, elderly people need some stamina, but not that of an olympic 10k

contender; some strength, but not that of a professional weight

lifter; and reasonable flexibility, but not that of a contortionist.

And we would like to be able to achieve this with the smallest

expenditure of extra calories.

I wonder how far " short bursts of high intensity exercise " totalling

about nine minutes a week (seven sessions every two weeks, with five

30-second bursts in each session) would go to satisfy these

objectives.

Rodney.

--- In , " " <crjohnr@b...>

wrote:

> This is pretty logical if you think about energy metabolism during

endurance type activities.

>

> The " wall " a classic marathon mile 20+ characterization of how it

feels to run out of stored glycogen can be pushed out two ways.

> First you increase your amount of glycogen stored, secondly you

improve your efficiency of burning fat and thus conserving glycogen

> since we typically only have a few thousand Kcal of Glycogen stored

despite carrying pounds and pounds of fat (except for you know

> who :-).

>

> A short burst type exercise would preferentially deplete glycogen.

Repeated deep depletion of glycogen will stimulate the body to

> increase storage capacity. However this will do nothing to improve

fat burning efficiency which is also important for maximum output

> during endurance events.

>

> I can easily imagine an experimental design that demonstrates

improved glycogen stores for brief exercise. I suspect this is of

> limited utility for actual endurance training which already

suggests working both mechanisms (speed work and slow runs). It's like

> doing the speed work only. OK if all you want to do is run sprints.

I guess it comes down to how you define endurance. Such training

> will allow you to run more sprints, but won't fully prepare you for

endurance activity.

>

> Perhaps more important how does glycogen storage capacity impact CR

goals. Increasing glycogen stored will actually prolong the time

> it takes for transition to fat metabolism (ketosis) during fasting.

I don't know if wide meal spacing approaches a true fast but if

> it does this could make it harder to get there.

>

> In general a CR friendly exercise doesn't burn calories. Likewise

mother nature rarely gives you something for nothing. Be sure this

> is really a CR positive. Less is less.

>

> JR

>

> -----Original Message-----

> From:

> [mailto: ]On Behalf Of Rodney

> Sent: Thursday, June 16, 2005 4:19 PM

>

> Subject: [ ] Short Bursts of High Intensity Exercise

>

> Hi folks:

>

> About a couple of months ago a study was posted here which showed

> IIRC that cycles of short, thirty second, bursts of exercise at full

> speed, with intervening four minute rest periods was just as

> effective at improving endurance performance as forms of exercise

> that involved much higher levels of caloric expenditure.

>

> Can anyone tell me where I can find that study? I searched the

> archive using the word 'exercise' and did not find it. Thanks.

>

> Rodney.

>

June 17, 2005

OK, but methinks that's a different goal. Rather than increasing your

glycogen capacity to increase that aspect of endurance performance. You

want to maintain or prevent losing previous youthful strength and

flexibility levels.

It seems this can be done with fairly modest amounts of resistance training

that are not very much of a caloric burden. The caloric burden comes in if

you increase muscle mass but that is not a large risk from modest workouts

while energy restricted.

JR

-----Original Message-----

From:

[mailto: ]On Behalf Of Rodney

Sent: Friday, June 17, 2005 8:16 AM