Enhanced air...does it help fatigue?

[DevonDiver]

And is that because the don't want to be bent or because of some mysterious unproven benefit of less fatigue?

What's bent? Is it black and white? Bent or not bent? Or is it grey? Shades of bent?

Do you believe we perfectly fine until some magical DCS line is crossed.... then we're injured?

Like crossing a road? We're either hit by a car or not.... either arrive at the other side in perfect health and well-being or get carted off in an ambulance severely injured or dead? No... it doesn't work that way. And doing an 'emu'; sticking your head in the sand overthe matter of sub-clinical DCS isn't a sound strategy.

I strongly believe that more information will arise in the future that shows harmful long-term consequences to decompression stress... sub-clinical DCS. It is also a 'yard-stick' for the effectiveness of your off-gassing... your comfort zone from DCS. And lastly, who the heck wants to be a washed-out zombie after diving??? I've got a life to lead thanks... catching zzzzz's all evening on the couch every night doesn't seem my idea of a great life (or great holiday, for those who don't work in diving...)

The concept of sub-clinical DCS is well understood and written about.

The medical definition of sub-clinical: "...relating to or denoting a disease which is not severe enough to present definite or readily observable symptoms".

Regards "unproven"... whilst no specific study had been done on nitrox/decompression stress/fatigue; we can extrapolate proven facts from other studies.

1. FACT: Ascent speed and stops influence microbubble scores.
2. FACT: Microbubble growth/elimination is heavily influenced by gas gradients.
3. FACT: Increasing %O2 increases gas gradient of nitrogen between tissues, lungs and ambient.
4. FACT: Increasing ppO2 and reducing ppN accelerates decompression.
5. FACT: Every diver contains inert gas bubbles on ascent, only the frequency/number and size vary.
6. FACT: Bubble size, not frequency/number determines DCS diagnosis.
7. FACT: Limiting bubble size, not frequency/number is the basis of most non-bubble deco algorithms.
8. FACT: The human body reacts to bubbles through an immune-system response.
9. FACT: Greater frequency of bubbles, of whatever size, creates a wider immune-system response.
10. FACT: Immune-system response alters blood/brain chemistry.
11. FACT: Blood/brain chemistry responses originating from immune-system activation result in..... FATIGUE!


More information here: Sub-Clinical DCS, Decompression Stress and Micro-Bubbles


Want quotes?

"... "mild DCI" is harder to define. This is largely because bubbles form, and can be detected in the venous blood, following a significant proportion of dives that do not result in symptoms that would normally be labelled "DCI". It is therefore hardly surprising that there can be a poorly defined boundary between wellness and mild DCI following diving. [...] It is not infrequent for divers to report highly non-specific and vague symptoms of variable latency, such as mild evanescent aches and pains, fatigue, demotivation and headache".
MANAGEMENT OF MILD OR MARGINAL DECOMPRESSION ILLNESS IN REMOTE LOCATIONS: AN INTRODUCTION TO THE PROBLEM.
S.J.Mitchell Ph.D, D. J. Doolette, Ph.D. DAN Remote Workshop Proceedings
​

"Inappropriate fatigue is a clear-cut symptom of subclinical decompression illness. I’m not a technical diver, Lord knows; but I see a lot of these guys. I send them out with decompression tables and they tell me what happens. They use their fatigue, their feeling of well-being – we called it constitution yesterday – as a major item in judging whether their decompression was adequate. The fact that they don’t have any joint pain or tingling or rash or anything is secondary. Their major thermometer as to whether they’ve been properly decompressed is how well they feel. And that has to do with the fatigue and inappropriate fatigue. So we have to keep this as a symptom, not as a side issue".
MANAGEMENT OF MILD OR MARGINAL DECOMPRESSION ILLNESS IN REMOTE LOCATIONS: AN INTRODUCTION TO THE PROBLEM.
Bill Hamilton in discussion. DAN Remote Workshop Proceedings
​

"Doppler monitoring has revealed the presence of gas phase bubbles in divers ascending even from relatively shallow dives. We have also all experienced symptoms such as headache and fatigue in the immediate post-dive phase which we have put down to overexertion on exiting the water etc. In more recent years, we have been told that these symptoms are those of subclinical DCI and we have lived with these, perhaps naively, thinking that because they are not associated with overt symptoms of DCI, they are not causing any damage and are nothing to worry about. However, enter the iceberg principle. Nine tenths of the damage may be invisible and cumulative".
THE TROUBLE WITH BUBBLES.
Richard Heads PhD. 9-90 Magazine: UK Diving in Depth
​

"...we know that bubbles are probably present after most dives, so we don’t have to exceed an M-value to produce bubbles in the absence of DCS. [...] Although an M-value may not have been exceeded, symptoms of decompression stress such as fatigue, malaise, drowsiness etc. could well be the result".
​

THE TROUBLE WITH BUBBLES.
Richard Heads PhD. 9-90 Magazine: UK Diving in Depth
​

LOL... this is in 'basic scuba', but it effects us all... especially those who haven't (yet) refined their diving behavior.

 

[Diver0001]

Nitrox reduces nitrogen absorption for a given dive profile (time and depth) compared to air. That, in itself, will decrease the propensity for bubbles, large or small.

I think Andy has put his finger right on the most important point. If you are doing the SAME profile, one with air and one with Nitrox then your inert gas loading on the Nitrox dive will be less and you could feel less fatigued after the dive. This could be a real effect based on the difference in nitrogen loading.

However, if you are making two dives, one with air and one with Nitrox and you are diving to (or beyond) the NDL's to the same *relative* extent with either gas then you're unlikely, in my opinion/experience, to observe any difference that isn't related to a placebo effect. After all, all things equal, the amount of N2 in your system will be in the same ballpark.

What I *have* noticed on the few dives in which I've decided to grind out deco on air is that the difference between doing that and using 50%, for example, is noticeable. I THINK this probably has to do with the pressure differentials during the decompression phase that allows higher Nitrox mixes to decompress faster. The computer compensates for this by shortening the decompression times but even at that I notice a difference. It could be related to (a) the dives having been longer (using air for deco can result in pretty long dives) or (b) it could be related to the models not being configured in exactly analogous ways or (c) it could be related to the "extra" deco we do during the last few minutes of the ascent after the last stop clears (including on the surface). The time is the same but using higher mixes of Nitrox continues to off-gas faster during those 3-5 min or so than air does.

R..

 

[DevonDiver]

What I *have* noticed on the few dives in which I've decided to grind out deco on air is that the difference between doing that and using 50%, for example, is noticeable. I THINK this probably has to do with the pressure differentials during the decompression phase that allows higher Nitrox mixes to decompress faster...

Two aspects to decompression:

1. Removing gas from the body.
2. Eliminating (micro) bubbles.

The time spent removing gas from the body (i.e. air versus 50%) should be irrelevant to a discussion on post-dive fatigue. After all, we're pretty much inactive... so that's just about 'being cold' for a short while longer. Do we normally get droopy-eyed and irresistibly sleepy after relatively short exposures to cold? No...

So that leaves the second issue: Microbubbles. Might I suggest that a timely removal of microbubbles from our bodies could prevent an immune-system response - thereby reducing/eliminating the fatigue generated from blood/brain chemistry changes brought about when our immune-system kicks in to action?


LOL.... still in 'New Divers...'

 

[Diver0001]

So that leaves the second issue: Microbubbles. Might I suggest that a timely removal of microbubbles from our bodies could prevent an immune-system response - thereby reducing/eliminating the fatigue generated from blood/brain chemistry changes brought about when our immune-system kicks in to action?

Must have missed something that you said before (admit to not reading all the posts) but I'm not aware of immune system responses to bubbles. I'll go back and read what you wrote and then follow up. The concept of a timely removal of micro-bubbles does ring a bell, however.

LOL.... still in 'New Divers...'

I know. I'll report for moving it and see what mods think.

R..

 

[dumpsterDiver]

I thought the immune system response was a huge issue. I was taught that it was a big factor over 40 years ago.

 

[halocline]

I know. I'll report for moving it and see what mods think.

R..

There's no reason to move this thread. The posts have been thorough, useful, and directly on topic, which is "does enhanced air help fatigue". A scubaboard rarity!

Many, many new (and new-ish) divers complain of post dive fatigue, and the info given in OW classes is basically "try using nitrox" and/or "live with it". This thread presents an opportunity for those divers to get some real insight into a common issue, complete with strategies that are useful to them. Moving the thread to an advanced forum would be a mistake.

 

[tursiops]

This is true, of course; for a given dive of X depth and Y time, the diver absorbs less nitrogen using nitrox compared to air.


<snipped>

Back to my initial point.... considering all three factors effecting decompression stress; nitrox use can provide a significant benefit in all three aspects.

Of course, you'd only notice that benefit if you'd otherwise subject yourself to decompression stress. If you don't, then you won't.

How many time am I allowed to "Like" this post?

 

[Rick Murchison]

My bride the Lovely Young Kat says she is less fatigued when using Nitrox than when using air.
I, on the other hand, can't tell a speck of difference.
She sez I'm insensitive
Bottom line... YMMV.
Rick

 

[scubadada]

I haven't dived air since a series of relatively shallow dives with my wife in 2010. I very often dive 4 dives per day for multiple dives, guess I'm doing OK. I never did notice any difference in fatigue between air and nitrox but the additional bottom time certainly is noticeable.

 

[Skeptic14]

Yeah butt, That's not how most people use nitrox (or a computer). They use the nitrox and computer to maximize their dive time (often anyway).

It's not so much about how much nitrogen you absorb on a given dive, it's about how much you surface with. So doing an extended stop mimics the effect of using nitrox in terms of lowering post-dive N2 load.

That might be true, hence me making a point to specify same diver and same profile.

That, however, only covers one issue - the amount of nitrogen absorbed. On-gassing isn't the problem. Off-gassing is the problem.

Simplistically, decompression stress is a product of 3 factors;

1. The amount of nitrogen absorbed (volume on-gassing).
2. The amount of nitrogen released (volume off-gassing).
3. The efficiency of nitrogen release (bubble formation).

It is wrong to consider nitrox use and decompression stress only in relation to #1, but ignore #2 and #3.

Sure, the off gassing is what matters but diving the same profile accounts for the off-gassing from what I can tell. The manner of safety stops and ascension rates.

What we aren't generally educated about (at least, until technical diving levels) is that nitrox also maximizes the efficiency of our off-gassing. It 'accelerates' our decompression. It helps remove nitrogen from our bodies at a faster rate. There's no magical barrier between recreational 'nitrox' and technical 'deco gasses'. Simply put, the higher the % O2, the more we accelerate the process of expelling nitrogen from our bodies. Nitrox 32% is higher than Nitrox 21% (air).

So.... we can see that for a given ascent and safety stop, nitrox will also remove more nitrogen than air does.

Using nitrox isn't just about absorbing less nitrogen for a given time/depth; it is also about releasing more nitrogen for a given ascent time/speed.

That's good info and I was unaware that off-gassing was more efficient based upon oxygen content, I only understood there would be less nitrogen to off-gas and thus the same profile would allow more to be removed by the time your surfaced. Is that because of the lower tissue saturation your body is more efficient at removing it?

But that point seems to solidify my point (if I had one) that the same diver diving the same profile will have less likelihood of DCS stress by using enriched vs air.