Mt Whitney Webcam
Mt Williamson Webcam
Who's Online Now
0 members (), 155 guests, and 16 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
CVAC Pods for acclimatization?
#27718 09/13/12 10:42 AM
Joined: Jan 2011
Posts: 286
B
Brent N Offline OP
OP Offline
B
Joined: Jan 2011
Posts: 286
Any of the medical folks on the board care to comment on CVAC Pods for acclimatization? These pods involve a protocol where you cycle through varying barometric pressures, working your way up to higher pressures. They aren't cheap to use--currently about $40 a session.

Here is a summary from another board.

Here are some relevant studies:

http://www.ncbi.nlm.nih.gov/pubmed/19364183

This study reported an increase of about 9% in arterial blood saturation after seven weeks, though this was at 4570 m. The greatest effects appear to be at high altitudes, higher than those at which GTs are generally raced (even the recently-concluded US Pro challenge did not race at elevations anywhere near that high, and much was made about how the elevations were greater than the Euros had ever experienced).

Arterial blood saturation refers to the proportion of oxygen-binding sites on the hemoglobin molecule which are filled. So it is a way of increasing oxygen transport that does not involve increasing red blood cells, but rather in effect increasing the efficiency of the red cells naturally present. However, that 9% increase might not necessarily result in an equivalent increase of oxygen delivered to the tissues; it depends on the efficiency of unloading the oxygen. Assuming it did, though, it would be equivalent to increasing hematocrit from 45 to 49. That would probably be better than blood doping in the passport era.

http://www.ncbi.nlm.nih.gov/pubmed/18091011

This study reported a 16% improvement in TT ability. It was not clear to me from reading the abstract whether this was time; the values decreased, consistent with it being time, but only gave two places, whereas time is usually given in minutes and seconds. Also, this performance increase was accompanied by only about a 3% increase in arterial saturation, which should not be nearly enough to account for that big an increase in TT performance.

http://www.ncbi.nlm.nih.gov/pubmed/19461532

Another study by the same group found no performance benefit, but the hypobaric treatment was only for 1 week and I believe did not involve the pulsing changes in pressure used in the CVAC. This same group has also studied the effect of blood doping on performance.



Re: CVAC Pods for acclimatization?
Brent N #27757 09/14/12 11:07 AM
Joined: Oct 2009
Posts: 742
K
Ken Offline
Offline
K
Joined: Oct 2009
Posts: 742
This is very interesting stuff!

One limitation in looking at these studies, is that the links are only to summaries. As they often say, the devil is in the details.

One immediate comment on the second study results. They report the results as significant at a P of <0.05, for everything measured, but don't cite the numbers.

For the non-statisticians, this is very critical, as a very small change will change the conclusions.

Also, the numbers used in all these studies are quite small, which can induce considerable bias.

In the last study, I was floored with the statement:
"Seven volunteers in the IHE group could not finish the 720-kJ time trial either at Pre-T or at Post-T. "

WHY?? That is a remarkable outcome. That indicates to me a substantial methodological flaw.

However, I think this whole topic bears considerable scrutiny.

Re: CVAC Pods for acclimatization?
Ken #27760 09/14/12 11:46 AM
Joined: Nov 2009
Posts: 1,037
Likes: 6
H
Offline
H
Joined: Nov 2009
Posts: 1,037
Likes: 6
Ken
Disclaimer - I have not had a chance to study this yet, but.......

In my experience, if one must prove a benefit with statistical maneuvering, and the result is not otherwise obvious, then the benefit is dubious.

This may be anti-scientific a bit, but a hefty dose of "Missouri" is useful. After all, Mark Twain said there are 3 types of lies; lies, damn lies, and statistics.

the studies may be fine, I am just pontificating


Edit-to be more helpful, here are some more thoughts on statistics. Something may be mathematically significant, but is it biologically significant? Big difference. On the opposite side of that arguement is this example: if the speed limit is 60 and you go just 1 mile an hr faster, then it may not be statistically faster but you might get a ticket, therefore the difference is meaningful. By that analogy, if a procedure done to help acclimatization has minor improvement, it still might give you a nudge enough to help

Re: CVAC Pods for acclimatization?
Ken #27761 09/14/12 02:03 PM
Joined: Jan 2011
Posts: 286
B
Brent N Offline OP
OP Offline
B
Joined: Jan 2011
Posts: 286
Thanks for jumping in, Docs. I found the first study in non-abstract form. I have not been able to find the others:

http://www.wemjournal.org/article/S1080-6032%2809%2970080-8/fulltext
full article


Re: CVAC Pods for acclimatization?
Brent N #27771 09/14/12 10:42 PM
Joined: Sep 2011
Posts: 1,158
Offline
Joined: Sep 2011
Posts: 1,158
Very small sample size, but interesting study. Correct me if I'm wrong here, I only skimmed the paper, but the theory seems to be that INTERMITTENT exposure to pressure change (simulating altitude up and down) can speed up acclimation? While the theory seems intriguing, it involves a lot of time and effort (30 hrs?), more hours than most people will spend planning the logistics of their Whitney hike. Correct me if I'm off.

In a perhaps related phenomena, I find INTERMITTENT doses of compressed O2 taken from a small pocket-sized oxygen canister to be EXTREMELY helpful while climbing above 10,000 ft.

Re: CVAC Pods for acclimatization?
SierraNevada #27774 09/15/12 06:10 AM
Joined: Nov 2009
Posts: 1,037
Likes: 6
H
Offline
H
Joined: Nov 2009
Posts: 1,037
Likes: 6
I finally got enough time with my spotty 3G coverage where I am currently to be able to skim the article...intermittently like the protocol itself. Some observations...

Theres was an attempt to show if 20 min sessions could work, others did longer

There was enough rapidity of pressure changes that ear symptoms were present, not like climbing a mountain, more perhaps like an airplane ascent or descent

The small changes in 02sat were similar to what we saw in our Aconcagua study in 2000 looking at different objectives. However, we found it hard to ignore the possibility there that fright alone at waking up and seeing one's own results be so low was enough to stimulate breathing and alter the result. This was not a factor in the current study.


I was pleased that they distinguished in their discussion between acclimatization (multiple factors) and acclimation (one factor). SierraNevadas response to short term canister O2 might be more the latter, say alleviation of fatigue from exertion or even exercise-at-altitude O2 desaturation rather than amelioration of AMS .Response in minutes rather than hours would suggest the improvement was more like, say a football player breathing O2 at sea level, rather than all the metabolic changes of AMS that take longer

The whole concept is interesting. I will be at the Exped Medicine Conference the end of this month . World reknown high altitude expert Peter Hackett will give several talks. I will ask him about all of this . Thanks, Harvey

Re: CVAC Pods for acclimatization?
Harvey Lankford #27784 09/15/12 04:43 PM
Joined: Feb 2011
Posts: 1,572
Offline
Joined: Feb 2011
Posts: 1,572
Originally Posted By: Harvey Lankford


I was pleased that they distinguished in their discussion between acclimatization (multiple factors) and acclimation (one factor). Thanks, Harvey


I, too would welcome observation of the distinction, if I could be sure of consistency. I have read two equally plausible distinctions between the words. One, as Harvey has said, that it is as between single and multiple factors, and the other that it is between environmentally induced (acclimatize) and laboratory-induced (acclimate) factors. I have even seen one source that claims that they are the same thing, since labs only change one factor and environment always changes more than one, or some such nonsense.

If Harvey's distinction is correct, then it seems that what we do before an ascent is to acclimate, as it involves adjusting to the single factor of altitude. On the other hand, the Portal is not exactly a lab, so that the second distinction would seem to control, meaning that we acclimatize. So what are we doing at WP before a climb: acclimating or acclimatizing?

(This should be fun!)



Wherever you go, there you are.
SPOTMe!
Re: CVAC Pods for acclimatization?
saltydog #27793 09/16/12 05:36 PM
Joined: Nov 2009
Posts: 1,037
Likes: 6
H
Offline
H
Joined: Nov 2009
Posts: 1,037
Likes: 6
Well, Salty, I did some homework!

I could not find my source for acclimation being just one factor. I thought it was on one of my slides for giving talks, but no. In fact, the texts I looked at tonight by the gods of high altitude medicine (Houston, Hultgren and West) do not even use the word acclimation. It seems to exist somewhere as a "US version" of acclimatization according to Wiki, but that is the first time I have read that. Perhaps it has become synonymous over time.

I did find this, just for clarification:

Accomodation - immediate effect such as increased ventilation. This is the most important factor for the bar-headed goose that wakes up one day in India and without acclimatization flys over the Himalayas to Tibet. It survives by hyperventilating, making its blood more alkalotic, and shifting its oxyhemoglobin curve.

Acclimatization The effect of many adjustments over time (days, weeks, or months) by the organism in response to a change(s) in environment. This means not just breathing harder, but changes on oxygen absorption in the lung membranes, changes in blood ph and aforementioned oxyhemoglobin curve, production of more blood, and intracellular changes where oxygen is downloaded.

There are two subcategories of acclimatization: natural(living there) and acquired (sojourners). Most of us are in the latter group.

For us, climbing Whitney could never be just one variable. Yes the altitude is the same, but weather, state of health, previous exposure, etc, etc, make every day different. Impossible to control just one variable unless one is a lab rat. Even then...

Adaptation- over many many years. It is said that true genetic natural selection takes perhaps 40 generations. It is argued that Andean high altitude dwellers have not been there long enough to be adapted well, although the math looks to me like they could. Physician Carlos Monge (Monges' Disease or Chronic Mountain Sickness) is a good place to read. Tibetans and other high altitude Asians,on the other hand, have lived there for much longer and may indeed be genetically superior in ways that go beyond having natural acclimatization from just living there all of their lives.

Hope this helps.

PS: West's text is the most recent 2007) and discusses Intermittent Hypoxia (IH) for pre-acclimatizing). All their studies were for hours at a time, not the quick 20 min dips in pressure like the pods do. Their conclusion was that it might be helpful, but that a few days acclimatizing in the usual fashion was good and much more pleasant. I will be at the Exped Med Conference in 2 weeks and ask high -altitude expert Peter HAckett about IH.

Re: CVAC Pods for acclimatization?
Harvey Lankford #27794 09/16/12 06:04 PM
Joined: Feb 2011
Posts: 1,572
Offline
Joined: Feb 2011
Posts: 1,572
Harvey: All of the discussion I have seen is secondary sources, no authority cited, so I won't even bother with links, with the exception of the following. I do not have access to the full article:

Article http://www.els.net/WileyCDA/ElsArticle/refId-a0001825.html

But I quote from the abstract:

Thermoregulation in Vertebrates: Acclimation, Acclimatization and Adaptation

John R Speakman, University of Aberdeen, Scotland, UK

Published online: April 2001

"Environments vary enormously in the thermal challenge they impose on the organisms that live in them. Some of these changes occur over very small temporal and spatial scales, and animals respond to these changes by acute modulations of their behaviour and physiology. More chronic changes in thermal environments, such as seasonal changes and latitudinal changes across the globe, require different responses. Three types of response have been recognized in both exothermic and endothermic vertebrates. These are termed acclimation, acclimatization and adaptive responses."

The third is clearly a long term genetic selection response. All are couched in terms of environment, and apparently deal with the single factor of temperature, so your guess is better than mine as to what the distinction might be.


Wherever you go, there you are.
SPOTMe!
Re: CVAC Pods for acclimatization?
saltydog #27796 09/16/12 06:29 PM
Joined: Nov 2009
Posts: 1,037
Likes: 6
H
Offline
H
Joined: Nov 2009
Posts: 1,037
Likes: 6
Originally Posted By: saltydog
so your guess is better than mine as to what the distinction might be.


It is a big blur




Edit: Subsequent responses to this thread were transferred here:   Portalization and Deportalization


Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.4
(Release build 20200307)
Responsive Width:

PHP: 7.4.33 Page Time: 0.033s Queries: 34 (0.028s) Memory: 0.6255 MB (Peak: 0.7198 MB) Data Comp: Off Server Time: 2024-03-28 19:46:16 UTC
Valid HTML 5 and Valid CSS