Fatigue and nitrox

[Valery]

Now i am lost, i started a thread because i was tyred 80% of the time after a deco dive on air.
I thought that using nitrox will fix the problem or deco with O2 but didn't want to do it because I didn't wanted to "hide" the problem with O2.
I thought that adding or decreasing deco (by using more or less conservatisme)could solve the problem, am I wrong?

 

[DocVikingo]

Now i am lost, i started a thread because i was tyred 80% of the time after a deco dive on air. I thought that using nitrox will fix the problem or deco with O2 but didn't want to do it because I didn't wanted to "hide" the problem with O2.

Hi Valéry,

If post-dive fatigue is materially decreased or even eliminated by the use of nitrox and/or increased conservatism of dive profiles, you almost certainly have "fixed" the problem, not simply "hidden" it.

Regards,

DocVikingo

 

[Scubagolf]

"Commercial divers report that nitrox mixtures reduce fatigue after a day's diving and make them more productive for the next day's work."

Diving Science - Essential Physiology and Medicine for Divers, Michael Strauss, MD and Igor Aksenov, MD, PhD, published 2004, page 40.

 

[DocVikingo]

"Commercial divers report that nitrox mixtures reduce fatigue after a day's diving and make them more productive for the next day's work."

Diving Science - Essential Physiology and Medicine for Divers, Michael Strauss, MD and Igor Aksenov, MD, PhD, published 2004, page 40.

In the absence of citation of the actual studies upon which this assertion is based, it really can't be considered evidence.

What have in mind is evidence such as:

1. Proceedings of the American Academy of Underwater Sciences 27th Symposium.Dauphin Island, AL: AAUS; 2008.

Measurement of Fatigue following 18 msw Open Water Dives Breathing
Air or EAN36

Scott D. Chapman, Peggy A. Plato

Department of Kinesiology, San Jose State University, One Washington Square, San Jose, CA 95192, USA

"SCUBA divers often report feeling fatigued upon conclusion of diving activities. Post-dive fatigue is thought to be induced by increased energy demands of submersion in a hyperbaric environment and decompression stress. Anecdotal reports indicate a reduction in post-dive fatigue when using enriched-air nitrox (EAN). The purpose of this double-blind study was to compare subjective fatigue levels experienced by SCUBA divers after two repetitive air dives and two repetitive EAN36 dives on separate, nonconsecutive days. Eleven male participants completed pre- and post-dive fatigue assessment using the Multidimensional Fatigue Inventory and a Visual Analogue Scale, while general health was assessed using the Diver Health Survey. Divers did tend to be more fatigued after diving; however, breathing gas mixture exhibited no statistically significant effect."

2. Measurement of fatigue following 18 msw dry chamber dives breathing air or enriched air nitrox. Undersea Hyperb Med. 2003 Winter;30(4):285-91.

Harris, RJ; Doolette, DJ; Wilkinson, DC; Williams, DJ.

"Diving to 18m produced no measurable difference in fatigue, attention levels, ability to concentrate or DHS scores, following dives using either breathing gas."

Regards,

DocVikingo

 

[Valery]

In the absence of citation of the actual studies upon which this assertion is based, it really can't be considered evidence.

What have in mind is evidence such as:

1. Proceedings of the American Academy of Underwater Sciences 27th Symposium.Dauphin Island, AL: AAUS; 2008.

Measurement of Fatigue following 18 msw Open Water Dives Breathing
Air or EAN36

Scott D. Chapman, Peggy A. Plato

Department of Kinesiology, San Jose State University, One Washington Square, San Jose, CA 95192, USA

"SCUBA divers often report feeling fatigued upon conclusion of diving activities. Post-dive fatigue is thought to be induced by increased energy demands of submersion in a hyperbaric environment and decompression stress. Anecdotal reports indicate a reduction in post-dive fatigue when using enriched-air nitrox (EAN). The purpose of this double-blind study was to compare subjective fatigue levels experienced by SCUBA divers after two repetitive air dives and two repetitive EAN36 dives on separate, nonconsecutive days. Eleven male participants completed pre- and post-dive fatigue assessment using the Multidimensional Fatigue Inventory and a Visual Analogue Scale, while general health was assessed using the Diver Health Survey. Divers did tend to be more fatigued after diving; however, breathing gas mixture exhibited no statistically significant effect."

2. Measurement of fatigue following 18 msw dry chamber dives breathing air or enriched air nitrox. Undersea Hyperb Med. 2003 Winter;30(4):285-91.

Harris, RJ; Doolette, DJ; Wilkinson, DC; Williams, DJ.

"Diving to 18m produced no measurable difference in fatigue, attention levels, ability to concentrate or DHS scores, following dives using either breathing gas."

Regards,

DocVikingo

I don't know if you could help but to make things easier supose that I dive on N21% will the increase or decrease of conservatisme on a VPM-B model make me less tired after a deco dive?

 

[bigdave1969]

If you can increase your O2, you will feel less tired, atleast i do, I never dive air anymore.

 

[miketsp]

Shoot me if I am wrong, but I thought that there was plenty of evidence to show that people breathing higher partial pressures of oxygen on dry land demonstate higher levels of energy and alertness.

The way I figure it, smaller numbers of nitrogen micro bubbles coming out of your blood can't hurt either. That's my highly non-scientific analysis.

A couple of years ago I posted a double blind study done with firefighters to see if EAN use was justified. (It should still be here somewhere).
The study showed noticable benefits only at aerobic levels of exertion.
So unless you're one of those divers constantly zooming around, in which case your SAC will be through the roof and you'll only get a short dive anyway, the real benefit of EAN is just the longer no-deco time.

 

[idocsteve]

Shoot me if I am wrong, but I thought that there was plenty of evidence to show that people breathing higher partial pressures of oxygen on dry land demonstate higher levels of energy and alertness.

The way I figure it, smaller numbers of nitrogen micro bubbles coming out of your blood can't hurt either. That's my highly non-scientific analysis.

Bang Bang you're dead.

No evidence exists to support the theory that breathing the higher partial pressures of 02 found in Nitrox gas mixes will give a person a higher level of energy or alertness.

Regarding less Nitrogen microbubbles coming out of your blood well yeah, that's why Nitrox is used in Scuba Diving. Less Nitrogen breathed, less Nitrogen absorbed, less Nitrogen bubbles to come back out again.

If you can increase your O2, you will feel less tired, atleast i do, I never dive air anymore.

Not true.

At least not in a tangible measurable physical sense. But don't underestimate the placebo effect!

"Commercial divers report that nitrox mixtures reduce fatigue after a day's diving and make them more productive for the next day's work."

Diving Science - Essential Physiology and Medicine for Divers, Michael Strauss, MD and Igor Aksenov, MD, PhD, published 2004, page 40.

Yes and during medical clinical studies patients often report improvement in their symptoms when they are unknowingly taking a placebo. Which is why proper clinical studies are done using a "control group" who are given a placebo, and a "test" group which is given the drug.

 

[gcbryan]

Now i am lost, i started a thread because i was tyred 80% of the time after a deco dive on air.
I thought that using nitrox will fix the problem or deco with O2 but didn't want to do it because I didn't wanted to "hide" the problem with O2.
I thought that adding or decreasing deco (by using more or less conservatisme)could solve the problem, am I wrong?

More conservatism will mean dives that are shallower or time at depth is less. Both will result in less nitrogen. Deco on O2 will result in less nitrogen as well.

If you are going deep enough to have substantial deco then deco on O2 will speed the offgassing.

If you are within Nitrox depths more than likely just modifying your profile will make you less tired...spend plenty of time shallow before you get out.

Diving Nitrox and using air tables at the depths where that is possible isn't likely to make enough of a difference for you to notice it...that's what the studies show anyway.

If you are tired do something to make you less tired....spend more time shallow and don't stay deep as long...if it's making you tired!

Most/many people when they first started diving were tired after diving...particularly after they started being able to go deeper and stay there a while.

Just using the tables, going to depth, and ascending directly to the surface or with a short 3 minute safety stop makes many people tired. Just think of it as the body working hard to get rid of the nitrogen. When you have allergies you are tired as well because the body is working hard to try to eliminate the allergens.

Instead of a 3 minute safety stop and then getting out of the water (which is entirely within the rules of the tables) start at 30 fsw and spend as much time slowly making your way up to the surface. The more time the better. If you are on a shore dive (multi-level) with things to look at this will be easy.

You may be surprised to find that you aren't so tired with this profile. If so you've fixed the problem.

 

[idocsteve]

If you are within Nitrox depths more than likely just modifying your profile will make you less tired...spend plenty of time shallow before you get out.

Most/many people when they first started diving were tired after diving...particularly after they started being able to go deeper and stay there a while.

This is the first time I have ever read or heard that going deeper can increase fatigue.

I'd like to hear about this previously unheard of (in my case) phenomena.