Re: Re: Walk, Don't Run

[Guest guest]

In a message dated 9/4/04 1:33:50 PM Eastern Daylight Time, aequalsz@... writes:

Maybe this

is why sprinters tend to retire at an earlier age than marathon

runners.

I believe it's because speed declines with age more than other physical attributes, like endurance or strength, do.

--

Ken

[Guest guest]

While I'm not sure what this has to do with CR, yes sprinters are less

efficient that distance runners. They also use upper body strength, swinging

their arms to counter their bodies up-down motion.

I suspect their earlier burnout is due to difficulties in maintaining high

levels of fast twitch muscle, but I'm just guessing.

JR

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

From: aequalsz [mailto:aequalsz@...]

Sent: Saturday, September 04, 2004 11:44 AM

Subject: [ ] Re: Walk, Don't Run

That's also true for marathon runners. The elite runners have very

little vertical motion compared to most of us, run of the mill

joggers. At the other end of the spectrum (of runners) are the

sprinters who take absolutely huge vertical leaps with each stride.

They generally aren't too concerned with minimizing overall energy

expenditures as are the marathon runners though. Actually at the

longer sprinting distances, such as the 200 and 400 meters, it is

advantageous to minimize energy expended, perhaps why

, with his rigid upright stride may have been the best 200

and 400 meter athlete ever.

Of course with sprinting, much larger forces are generated versus

when marathon running. (I think someone on this web site mentioned

that the laws of thermodynamics are always obeyed even for

biological systems. Although no - or negligible - mechanical work

is done holding a 5 pound weight stationary at arm's length for a

hour, internal energy is expended in generating the force required

to do so and is most likely manifested as heat energy.) Maybe this

is why sprinters tend to retire at an earlier age than marathon

runners.

Aequalsz

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[Guest guest]

In a message dated 9/4/04 4:50:02 PM Eastern Daylight Time, aequalsz@... writes:

On a personal note, I try to keep my HGH supply high by ending my

treadmill runs with a 150 yard "sprint". Read somewhere

that high intensity exercise promotes the production of HGH but I

don't know how effectively it does this.

You are quite right, though I can't find any study showing the actual size of the effect.

for using some treadmill-like machine, I found:

J Clin Endocrinol Metab. 1992 Jul;75(1):157-62.

Effect of low and high intensity exercise on circulating growth hormone in men.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=pubmed & dopt=Abstract & list_uids=1619005

PMID: 1619005

"GH did not increase significantly from preexercise baseline during low intensity exercise" but "A minimum duration of 10 min, high intensity exercise consistently increased circulating GH in adult males."

High intensity is defined therein as being anaerobic (above Lacate Threshold). But what's the size of the effect? Given in the abstract is that "mean increase above baseline of 7.7 +/- 2.4 micrograms/L" but the baseline itself is not given so as to be able to compute a % increase.

with weights, we have:

Eur J Appl Physiol Occup Physiol. 1984;53(1):31-4.

Growth hormone responses during intermittent weight lifting exercise in men.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=pubmed & dopt=Abstract & list_uids=6542499

PMID: 6542499

"Exercise I consisted of seven sets of seven vertical leg lifts at 85% of the subject's Seven Repetition Maximum (SRM)" This did show a GH elevation.

But, "No significant elevations of GH occurred in Exercise II" with 1/3 the weight and 3 times the repetitions.

However, when considering the age of the subjects:

J Clin Endocrinol Metab. 1992 Aug;75(2):404-7.

Age-dependent effect of resistance exercise on growth hormone secretion in people.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=pubmed & dopt=Abstract & list_uids=1639942

PMID: 1639942

Subjects are either ~27 or ~72 yrs old, using Nautilus equipment at 70% of 1RM. "In the young subjects, GH responses were nonsignificant at 60% and increased progressively at 70% and 85% of 1RM. No significant effect of exercise intensity was observed in the older subjects."

Serum GH values were ~1/3 less in the elderly to begin with.

I'd be interested in finding something about emotional state during the exercise and how that affects GH release. One study suggested that high levels of epinephrine and nor-e result in higher levels of GH. (PMID: 10926647)

--

Ken