Diving "Conservative" vs Nitrox

[arkstorm]

It would be great if we can get @Dr Simon Mitchell or @Duke Dive Medicine to chime in on the current state of the science in the understanding of post-dive fatigue and whether the use of EAN or a more conservative dive computer setting can be a factor in reducing it?

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[scubadada]

It would be great if we can get @Dr Simon Mitchell or @Duke Dive Medicine to chime in on the current state of the science in the understanding of post-dive fatigue and whether the use of EAN or a more conservative dive computer setting can be a factor in reducing it?

​

Is there any new quality data related to this issue, I think not?

 

[SetheryJ]

Are you stating that ascent rate doesn't matter?

Really? Please read some books.

So do you dive nitrox on every dive?

This I don't understand? It's been proven time and time again people move too fast, especially in the last 20'. Why would telling someone to slow that down and look at other aspects of their diving be a bad thing?

I never said BAD (which to me would convey some form of DCS). I said tired / bad meaning fatigued / worn out. And I'm not saying don't use nitrox, I think nitrox is a great tool. I'm saying I think one should figure out what it is about their diving that causes them to feel tired in the 1st place before just throwing a different gas at it. Sure nitrox will probably work, but let's start with what gf's do you dive, how fast do you think you ascend? Hell, let's look at some post dive analysis and see if we can't figure this out.

My point is you don't have to feel like crap diving air. You really shouldn't. I'm not saying "never dive nitrox".

To me if the same diver is diving in a way that air makes them tired then they should probably look at their diving habits vs just what type of gas they use?


I never said avoid nitrox. How is using air and going into 15 min of deco any different than using nitrox and going into 15 min of deco?? Obviously the dive times have changed, but how is the end result any different? Somehow though I'm magically a safer diver with 15 min deco obligation and a different gas in my tank?

Listen, I will dive air, I will dive nitrox. I think nitrox is a great tool for what it is. I use it for the dives that I plan that I think it's warranted. It just depends. Do I think it's needed in a pool, or a 20' dive to find something for someone at the dock? No. Do I think it's needed for a week long trip diving to 60' 100 times to look at fish,.... of course. But I wouldn't use it just because I felt tired. I would take a hard look at why I feel tired in the 1st place and try to make some changes, and then maybe also incorporate nitrox.

Maybe I should have stated it more clearly. We were on a 15' dive on Sat, buddy said his buddy always dives nitrox, no matter what the depth / dive is. He said he always felt tired on air. To me this says something else is going on. My argument was that if you change the way you dive on air I bet you would feel much better.

I agree nitrox is a better gas (that was never my argument). Understanding why you get tired on air is just a better place to start.

Yes, I dive nitrox on every dive, I have a nitrox blending station on my back .

Your lack of understanding on the topics of DCS, tissue saturation, on gassing and off gassing, decompression theory, et al are a travesty. And yet you try and argue your incorrect point.

I am a little confused about some of this discussion.

The primary purpose of using nitrox is to extend dive times. Using it when there will be no additional dive time has the benefit of less nitrogen loading in the tissues.

People seem to be arguing that another choice would be simply diving air with a more conservative computer setting yielding a shorter dive time. That seems to me to be saying you get the same benefit of nitrox by simply doing shorter dives. Is that what is being argued?

How would breathing technique take in less inert gas?

How has this been proven? I am not familiar with the studies that have proven this. Could you provide links?

From the DAN article:

Harris: No. Three articles in the peer-reviewed literature (see the first three in the references sidebar) contribute evidence to the nitrox and fatigue question, but I am not convinced that the size and power of any of them have addressed the problem comprehensively.​

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He's being very polite. The studies I've looked at were, IMHO, worthless. With some admitted exaggeration, they're like "Let's have 3 people do a 30 minute dive to 60 feet on air and 3 people do a 30 minute dive to 60 feet on nitrox and compare how they say they feel afterwards." To test an issue like this, you have to be able to push the envelope.

For me personally, I think of how I felt at the end of my first liveaboard trip (wiped out after 3 days on air) to the way I felt after every full week trip since (feeling great after 6 days on nitrox). It would be very difficult to make a test of that duration.

I just wanted to quote some of John’s stuff because it’s pretty clear the OP needs to reread these posts 1000 times. Thanks to John for being polite .

 

[RobPNW]

I did a 2 week trip, similar diving, same number of dives per day, 1 week on air and 1 week on nitrox. I didn't feel any difference. But if given the option, I'll dive nitrox to lessen the nitrogen absorbed. That's as scientific as I get. I'll follow the more sophisticated discussion and hopefully learn from the rest of you.

 

[The Chairman]

Is there any new quality data related to this issue, I think not?

Of course, not. They gots papers. Well. OK, you've got papers too. They just don't know it. Me? I'm a putz. I just know what works for me. That's about all I need, too!

 

[inquis]

I did a 2 week trip, similar diving, same number of dives per day, 1 week on air and 1 week on nitrox.

Were you mostly diving to NDL on all dives, so the nitrox dives were longer? Or were you mostly gas-limited, so dives were comparable length?

 

[RobPNW]

Were you mostly diving to NDL on all dives, so the nitrox dives were longer? Or were you mostly gas-limited, so dives were comparable length?

Gas limited. Average dive time about the same.

 

[Cthippo]

I think you guys are barking up the wrong tree here. I suspect it has nothing to do with ongassing or exertion or ascent rates or even diving.

Nitrox makes yoy feel better because it is more oxygen. I strongly suspect you can get the same effect from sitting in your living room breating off a nitrox tank because you are getting more than 21% O2. By the time you are old enough to afford this hobby we mostly have some blockage and age related breakdown of our various pipes and systems and we don't circulate as well as we should. Breathing in extra oxygen gets it to the places that aren't getring quite enough most of the time and those cells are happy.

 

[rob.mwpropane]

Morning, lots to unpack here and work got super busy with this nice weather. I should have waited to post something like this when I had more time. Apologies.

People seem to be arguing that another choice would be simply diving air with a more conservative computer setting yielding a shorter dive time. That seems to me to be saying you get the same benefit of nitrox by simply doing shorter dives. Is that what is being argued?

My argument is that you can safely conduct a dive on air and feel fine afterwards. My argument was that if you're tired after one dive on air then there's something off about your diving. Let's take a look at that, how "liberal" is your computer set to, how fast do you ascend? To me, (and maybe I'm wrong) if someone feels tired after one dive on air then we should get to the bottom of that vs "just switch gas".

How has this been proven? I am not familiar with the studies that have proven this. Could you provide links?

No, I don't have any links, but we've had a few discussions on here where someone starts diving, they get a little more into it, they get a dive computer that can track their dive much better, then they realize after looking through some post dive analysis that they were moving too fast in their ascent.

That's not really evidence, maybe anecdotal at best, but that's also been my experience when switching from rec to tec.

Not to mention the people that I can see at the quarry hanging out for a SS only to bolt to the surface and be there at 3m15s after starting the SS. What's the rule taught? No faster than 30' / min? I've seen it stressed on here it's much better to crawl to the top then go by any arbitrary number. I feel a lot better if I crawl to the surface in the last little bit. Maybe in my earlier days of diving if someone told me to dive nitrox instead of slowing down that would have worked too?, but I would think it would be better to understand where the tired comes from (hence this discussion).

My question is...do you think he's diving differently on nitrox than he is on air? If he is, then why would he? Divers generally dive the same way all the time. If he's moving "too fast" in the last 20 feet on air, he's almost certainly doing the same thing on nitrox. So for me, that negates your argument.

Personally, I am one of those that say I am less tired on nitrox than I am air. I generally use air when diving locally in quarries or do a 2 dive charter at the coast on a single day. For these types of dives I feel that nitrox is an unnecessary additional expense. But on a week long dive trip, I prefer nitrox for several reasons, one of which is I just don't feel as tired towards the end of the week as opposed to diving air. My wife says the same thing.

Most divers want to make their dives as long as possible. Why would anyone want to increase the conservatism of their DC and shorten their dives?

If I had to guess I would think he's diving the same tank so now he's more limited by gas. I don't know if it negated the argument, with the same tank doing the same dive but using nitrox he will have less nitrogen.

I can't see how making such an evaluation is a "band-aid" in one case but acceptable in the other.

To me nitrox is a tool. If I want more BT or less deco then it makes sense. If I'm doing one dive on air and I feel like crap then I should probably get to the root of why that is?

If I constantly have headaches every day and I just take motrin and never try to figure out why I'm not sure motrin is really an answer... to me it's just a "band-aid"?

For me personally, I think of how I felt at the end of my first liveaboard trip (wiped out after 3 days on air) to the way I felt after every full week trip since (feeling great after 6 days on nitrox). It would be very difficult to make a test of that duration.

Again, I agree 100%. Nitrox is a great tool and in certain situations it's perfect for the job at hand. For a livaboard or a week of diving (I think I even said it in an earlier post) it makes perfect sense. In my original post (which I should have probably stated more clearly) this was one guy, doing one dive and feeling tired afterwards on air. No livaboards involved.

Really? Please read some books.

Yes, I dive nitrox on every dive, I have a nitrox blending station on my back .

Your lack of understanding on the topics of DCS, tissue saturation, on gassing and off gassing, decompression theory, et al are a travesty. And yet you try and argue your incorrect point.

I don't think I've been ignorant in any of my posts I'm not sure why you feel the need to be? Read a book? Really? Man I am constantly reading, constantly learning, constantly trying to better myself. It's a hell of a ride and I'm not even close to done yet.

If I incur 15 min of deco on air, or 15 min min of deco on 32%, should I feel more tired on the air dive? Do you feel "better" diving CCR than you used to on OC? Do you think it's because of the elevated ppO2 you're breathing all the time?

To me, if I'm tired after one dive (on air) then I should take a hard look at what I did before the dive and during the dive and figure out why that is, that's all I'm saying. If I did an NDL dive (which I'm assuming the guy that I'm talking about is doing, I've never met him) and I felt tired I hope that I would take a hard look at why instead of just throwing a different gas at it.

So if a diver came to you (that you've never met) and told you they always feel tired after a dive using air your go to would be "just switch gas, you'll be fine"? You wouldn't dig a little deeper and find out what he's running, what's his plan looks like? How "liberal" his computer is, etc?

I just wanted to quote some of John’s stuff because it’s pretty clear the OP needs to reread these posts 1000 times. Thanks to John for being polite .

I have always appreciated @boulderjohn posts. I thought that's why we come here.. to have an open discussion without being ridiculed. I am always open to the idea in any discussion that I might be wrong. I am truly happy for you that you've arrived... I'm not there yet!

This topic comes around time and time again, in one form or another, and you could do any number of things -- dive more conservatively; more slowly as others have already mentioned (in a big hurry, are you?), along with a longer safety stop; and / or set those increasingly complex computers accordingly.

I have used nitrox, well before it was ever approved by any of the money-grubbing agencies (one of whom even offers -- damn -- "mermaid" training), when none of them green-lit EAN use at all; and dismissed it, as Vance Harlow described, as "voodoo gas" -- never mind that it had been around since the nineteenth century.

In that entire time, I have never noticed a whit of difference, in terms of some great "lack of fatigue" or "increased energy," whatever subjective description, over an enormous number of dives, of nitrox use over air -- though an old college friend debated that topic with me, over the years.

That was, until he got away from his daily Macintosh workout and unceremoniously dropped thirty pounds along with the absurd ponytail and aging hipster beard-o combo; ended his three martini lunches; and most important of all, jettisoned his harridan of a wife -- who could truly suck the air (or EAN, if you will) out of a room.

He now dives -- eh, primarily on air, once again -- and enjoys it, especially minus that additional Oz two-hundred dollar, plus, live-aboard nitrox fee <º)))>< . . .

This also a really good point, I hadn't thought about his age or what shape he's in. I've never met him.

 

[boulderjohn]

I have used nitrox, well before it was ever approved by any of the money-grubbing agencies (one of whom even offers -- damn -- "mermaid" training),

I know this is off topic, but since you brought it up...

I am pretty sure (could be wrong) the first agency that offered mermaid training was NAUI, followed soon after by SSI. PADI did it after that. I don't know about other agencies.

There are evidently people who want to have training in using those mermaid tails, perhaps to get jobs doing the mermaid shows in aquariums. If people want such a service, what is wrong with someone providing it? By "money-grubbing," are you saying that the instruction should be provided free of charge? Do you resent the fact that instructors are paid for the work they do?

I went to the hardware store recently to replace one of my power tools. Can you believe it? The money grubbers wanted me to pay for it!