Fatigue and nitrox

[gcbryan]

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?

Feet Sea Water or in your case msw Meters Sea Water.

 

[Valery]

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..

What's a PFO?

Well isn't there any books or document about this subject??? How on earth could such a sport be left without any scientifical studies. I feel like we are living in the 1800's

 

[idocsteve]

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.

You say it's incorrect to argue that nitrogen loading does not affect a diver's post dive fatigue level, which is a double negative that can be simplified to:

"Nitrogen loading increases a diver's post dive fatigue level."

Show me a study that conclusively proves that.

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.

Yeah well that's why I said that I was reaching a bit by making a connection between those two things and I added the disclaimer "Please correct me if I'm wrong".

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.

 

[schaffld]

What's a PFO?

PFO = Patent Foramen Ovale

A hole in the wall separating the left and right atria in your heart. It's necessary during our fetal development but usually closes shortly after we are born.

In some people, it can remain open throughout their whole lives without any symptoms. Others may need surgical correction very early in life.

In other people, symptoms (increase fatigue, shortness of breath) may show during exercise/exertion... such as diving.

that's a PFO in 75 words or less...

 

[Bubbletrubble]

You say it's incorrect to argue that nitrogen loading does not affect a diver's post dive fatigue level, which is a double negative that can be simplified to:

"Nitrogen loading increases a diver's post dive fatigue level."

Show me a study that conclusively proves that.

@idocsteve: Please pay attention to the qualifying language in my posts. "...pretty difficult (and almost certainly incorrect)..." was purposefully inserted into my statement.

Furthermore, there's a difference between what I wrote and your simplification. What I wrote places the burden of proof on the person hypothesizing that nitrogen loading does not affect a diver's post-dive fatigue level. Your simplification places the burden of proof on the person hypothesizing that the nitrogen loading increases post-dive fatigue. The difference is in how the statement was phrased.

Valéry's significant post-dive fatigue is very likely related to decompressing too quickly. An extended safety stop would probably help with that. Another strategy would be for her to limit her nitrogen loading in the first place.

 

[The Chairman]

I am not a medical doctor! I fix sick Networks. However, I learned something from a Dan presenter a few years ago.

Most recreational divers suffer from Type II DCS (neurological). Marked fatigue is also a symptom of cub-clinical DCS as well as more advanced stages of DCS.

He then went to point out that the half times for blood and neural fluids are pretty similar (3-5 minutes). It is my humble belief that anything to reduce N2 during and after the dive will also reduce fatigue. However, I believe that the rate of ascent has more to do with this than anything else.

If you are diving for 5 cycles, you are 97% saturated which is pretty durn close to being fully saturated. For blood and neural fluids, this is only 25 minutes. If you have spent 25 minutes at 99 FSW, your blood and neural tissues are close to being at 3.16 ATA_N. A three minute stop at 15 FSW will result in you surfacing with 2.17 ATA_N in those tissues.

However, if you did a deep stop of 3 min @ 50FSW and then a 5 min shallow stop at 15FSW then you would surface with 1.65 ATA_N which is a difference of over half an atmosphere. Going the Deep stop route results in having about 60% of the excess N₂ compared to doing only the safety stop.

For 32% the figures would be:

25 min@ 99FSW: 2.72 ATA_N
3 Min safety stop only: 1.87 ATA_N
3 min deep stop & 5 min shallow stop: 1.42 ATA_N
3 min deep stop & 5 min shallow stop on O₂: 0.74 ATA_N

It should be noted here that:

• I am only looking at ONE tissue group (Blood/Neural Tissues) since it's more likely that I will suffer Type II DCS.
• I am using 3 mins as the half time for these tissues. Dr Deco has a lot better data for this.
• I am rounding where it makes sense to me.
• Doing a deep stop with a full five minutes at my shallow stop works well for me. I can stay awake on the drive home.
• I am not a medical doctor.

 

[CaboJim]

This appears to be subjective. However, my experience is that if you're doing more than 2 dives in 1 day, nitrox will keep me from getting fatigued by the 4th or 5th dive.
When I go dive trips, I like to get in at least 4 dives a day. So I will be diving nitrox...

 

[idocsteve]

@idocsteve: Please pay attention to the qualifying language in my posts. "...pretty difficult (and almost certainly incorrect)..." was purposefully inserted into my statement.

Yes I'm sure everything you wrote, you wrote "on purpose".

If it's "certainly incorrect" then please explain why and provide at least one study or other relevant link that supports your position that Nitrogen loading during a dive is positively associated with fatigue other than because it seems to make sense to you and/or you feel better after diving with Nitrox as compared to air.

 

[idocsteve]

This appears to be subjective. However, my experience is that if you're doing more than 2 dives in 1 day, nitrox will keep me from getting fatigued by the 4th or 5th dive.

You meant to say that you "think that Nitrox will keep you from getting fatigued by the 4th or 5th dive, even though there is not one single bit of conclusive evidence to support that statement and the fact that some divers "feel better" after diving with Nitrox as compared to air is probably nothing more than the well known and universally accepted phenomena known as "The Placebo Effect".

 

[islanduni]

If you dive it commercially you feel better as far as elbow and shoulder cramps go. As far as more energy at the end of the day? I'm beat!