Fatigue and nitrox

[gcbryan]

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.

It's not the going deep per se, it's just nitrogen loading however you get it. Going deep is the fastest way of course.

Try doing a dive where your nitrogen loading is close to the NDL's and then ascend at 30 ft/min, do a 3 min stop at 15fsw and get out and repeat all day if you are doing multiple dives.

If you feel tired and it's not just because you had long surface swims or long walks in heavy equipment to get to the water then try the same dives with 15 minutes spent (at the end of the dive) just messing around looking at small marine life in the range 30 fsw to the surface. You will most likely not feel nearly as tired after the dives.

In effect you are allowing your body to decompress even though there was no decompression obligation. Your body still has to offgass even though it didn't exceed the DCS limits.

It's just a matter of find a dive profile that works for you. I try to end all dives this way. Along with doing the deeper part of my dive first it just makes the rest of your dive one long decompression stop (s).

 

[Valery]

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.

Thank for your answer, I'll try adding deco time in the shallow zone next time I dive. I'll tell you if it fixed the problem.

Sorry my english isn't very good, what's fsw?

 

[idocsteve]

It's not the going deep per se, it's just nitrogen loading however you get it. Going deep is the fastest way of course.

Well bryan, now it sounds to me like you're into the realm of speculation and theory and not facts.

Because it seems, to me, that you're saying increased Nitrogen absorption equates to increased fatigue, and then it would follow (please correct me if I'm wrong), that diving Nitrox as compared to air would result in less fatigue, all other factors being equal.

And that, is at best an unproven and highly controversial theory.

 

[Brishar]

I feel less fatigued. I feel warmer. If it's all in my head, well, at least something is in there after all. But it would be nice to have a study or two confirm the same results.

Oh well.

 

[Valery]

Well bryan, now it sounds to me like you're into the realm of speculation and theory and not facts.

Because it seems, to me, that you're saying increased Nitrogen absorption equates to increased fatigue, and then it would follow (please correct me if I'm wrong), that diving Nitrox as compared to air would result in less fatigue, all other factors being equal.

And that, is at best an unproven and highly controversial theory.

Are you saying that Nitrogen is not resonsible for feeling tired after a dive???
If yes then what a F%$^ is making me tired?

To explain more what's happening to me, 80% of the deco dive I do, I feel tired (really really sleepy).

 

[idocsteve]

Are you saying that Nitrogen is not resonsible for feeling tired after a dive???
If yes then what a F%$^ is making me tired?

To explain more what's happening to me, 80% of the deco dive I do, I feel tired (really really sleepy).

Valéry I wish I could give you a definite answer but I really cannot say for sure. All I can tell you is that there is no evidence whatsoever to support the theory that diving with a higher 02 percentage will decrease fatigue following a dive, and it appears that Bryan is saying it does although I'm admittedly not 100% sure that is what he's saying.


Maybe its because Scuba Diving is a very physically demanding sport.

 

[Valery]

Valéry I wish I could give you a definite answer but I really cannot say for sure. All I can tell you is that there is no evidence whatsoever to support the theory that diving with a higher 02 percentage will decrease fatigue following a dive, and it appears that Bryan is saying it does although I'm admittedly not 100% sure that is what he's saying.


Maybe its because Scuba Diving is a very physically demanding sport.

I've well understood this and I'm not asking whether or not decoing with 50% or more oxygen will make me feel better.

I'm 34 and in very good condition, I use to do a lot of sport and never felt sleepy what so ever. I really don't think that lifting my 30kg equipment or palming under water is sending me to bed.

I've talked to my instructor who says that mainly it's the nitrogen and the deco that are making me feel this way.

That's why I thaught that maybe my deco profile needed adjustment (more or less deco).

I'm going to change 1 factor each time I dive to see what makes me feel better. I'll start with adding more deco time in the shalow zone.

 

[idocsteve]

I'm 34 and in very good condition, I use to do a lot of sport and never felt sleepy what so ever. I really don't think that lifting my 30kg equipment or palming under water is sending me to bed.

I've talked to my instructor who says that mainly it's the nitrogen and the deco that are making me feel this way.

Well again, there seems to be a connection between what your instructor is saying about nitrogen and the unproven theory that diving with higher 02 will reduce fatigue, but that's a circular conversation that can't go anywhere because no one really knows for sure.

Regarding why you might feel more tired after diving despite your good physical health and lack of fatigue in other sports, my non technical completely off the top of my head explanation is that there's something about Scuba Diving that just makes people tired...lol

 

[Puffer Fish]

I've well understood this and I'm not asking whether or not decoing with 50% or more oxygen will make me feel better.

I'm 34 and in very good condition, I use to do a lot of sport and never felt sleepy what so ever. I really don't think that lifting my 30kg equipment or palming under water is sending me to bed.

I've talked to my instructor who says that mainly it's the nitrogen and the deco that are making me feel this way.

That's why I thaught that maybe my deco profile needed adjustment (more or less deco).

I'm going to change 1 factor each time I dive to see what makes me feel better. I'll start with adding more deco time in the shalow zone.

The problem with simple studies is that they may not be checking in the correct area or the right things.

However, there is a big difference between "feeling better" or less fatigued and what you seem to be discribing.

We do know of several things that might cause one to be very tired after a dive, a few of which are:

1. Blood sugar levels...

2. Hyperventilation (and a whole variety of similar issues from high CO2 retention to low CO2 retention)...

3. Have a PFO

4. Be more susceptible to DCS. Remember a small percentage of the human population will have DCS issues, even when they follow the tables.

If you are doing deco diving, then you will have some level of micro bubbles in your system... how your body will react to that varies trememdously..

The problem is, no one on the internet would be able to answer why..and the possiblities vary from trivial to pretty important..

 

[Bubbletrubble]

Valéry I wish I could give you a definite answer but I really cannot say for sure. All I can tell you is that there is no evidence whatsoever to support the theory that diving with a higher 02 percentage will decrease fatigue following a dive, and it appears that Bryan is saying it does although I'm admittedly not 100% sure that is what he's saying.


Maybe its because Scuba Diving is a very physically demanding sport.

I think idocsteve's comments are misleading. To clarify, there is no conclusive evidence to support that using a 32% nitrox mix significantly decreases post-dive fatigue when compared to a regular compressed air mix. It is flat out wrong to take this previous statement/conclusion and hold it up as evidence that nitrogen has no bearing at all on post-dive fatigue.

I'm all for looking at evidence-based diving practices...but it's pretty difficult (and almost certainly incorrect) to argue that nitrogen loading does not affect a diver's post-dive fatigue level.

Yes, Valéry, your post-dive fatigue could be due to physical exertion during the dive. But, to a certain extent, it may also be due to the nitrogen loading. In fact, depending on your level of physical condition, the magnitude of the nitrogen loading effect may far outweigh the physical exertion effect.

Puffer Fish makes some very good points above.