Enhanced air...does it help fatigue?

[DevonDiver]

Not really. Have you read those studies? They are irrelevant to multiple dives a day over multiple days, which is when the anecdotal evidence points to an effect of fatigue lessening.

There needs to be two studies, linked:

1. Decompression stress (bubble score) across a range of dive parameters (multi-day, repetitive dive, saw-tooth profiles, ascent strategies and nitrox use) to determine the sub-clinical DCI impacts of predictable diver behavior. This would produce knowledge that identified hi - med - lo range decompression stress dive behaviors/factors.

2. The impact of decompression stress (a range of bubble scores; hi - med - lo) upon perceived post-dive vitality and energy. The crux of this study would be to measure decompression stress versus fatigue.

As of now, the science of diving has focused only on what is necessary to prevent (tolerably reduce!) clinical DCS occurrence. In short, it keeps divers out of a chamber, but doesn't care to what extent they are 'zombified' after diving. It has largely ignored sub-clinical wellness and vitality. As more becomes known about the long-term health impacts of repeated / regular / routine exposure to decompression stress, that may change... (we might hope!).

Technical divers have long been aware of the existence of decompression stress. We use it as a 'yardstick' to determine what is optimal for us in our dive planning. Whether we feel 'fizzy', drowsy or vital after diving... is a clue as to whether we are getting our gradient factor settings, gas selection ascent profiles better or worse. But still, the emphasis is on keeping ourselves out of the chamber; not (often) on whether we are protecting ourselves against potential long-term medical consequences.

In contrast, recreational divers seem to have taken the issue of post-dive physical/mental dilapidation with a pinch of salt. It has become 'usual and expected'. The blame for post-dive sleepiness and lethargy goes on 'cold', or 'exertion' or 'fresh air'. Nobody gets a chamber ride, so nobody cares. They will.... if any of the current questions linking repetitive/routine decompression stress with brain lesions, osteonecrosis etc happen to be proven.

 

[AdivingBel]

I dive nitrox when diving muliple dives on multiple days. It makes me feel better 'cause I get more bottom time on my vacations and THAT makes me feel better (& happy). That's not a placebo effect. Haven't really noticed much on the less tired front.

 

[oly5050user]

There's no scientific evidence of less fatigue using EAN. You being exhausted has probably more to do with inexeperience in diving.

Could also be fatigue caused by being cold and experiencing core temperature getting low, or , he did do 4 dives in 1 day. How close to NDL limits? Questions I would ask is did he wear a wet suit? Use a computer? What kind of profile was dove?
i seriously doubt nitrox would eliminate fatigue. Works more like a placebo in my experience.

 

[halocline]

I am new to diving, 12 dives total....

I read somewhere that using enhanced air can lower the fatigue felt at the end of a dive. I wonder if I would have been able to handle the four dives in one day if I had been using nitrox?....

Maybe just putting in more time at the gym would be the answer. Opinions?

I think Devon Diver's posts in this thread do a good job of explaining the likely reason that nitrox use is often perceived as reducing post-dive fatigue. Putting it on a bumper sticker, a likely contributor to post dive fatigue is simply increased blood nitrogen levels upon surfacing. (He went into a lot more detail) Nitrox reduces those levels IF you do an identical profile as you would on air.

However, there's a good, simple way to reduce N2 levels on surfacing in recreational diving without using Nitrox, and that's by doing a very long safety stop and then proceeding to the surface very very slowly. Try it, you'll be surprised at how well it works. You might try 3 minutes at 15-20 ft, then an additional 7 minutes at 10-12 feet, then take a full minute to surface from 10 feet. If you have a computer, it probably has a N2 loading bar graph. Don't surface until you're in the 'green' segments of that bar graph. On repetitive dives, this will probably mean longer stops at 10-15 feet.

The deep stop idea and avoidance of up-down-up-down profiles are related to the formation of microbubbles in the blood. You might try reading more about this, but even if you don't fully understand it (I don't) the practical answer is easy to understand; manage your profile so that you start deepest and gradually work your way to shallow. If you are on a dive that has a deep 'square' profile, do a brief stop at approximately half your depth before proceeding to your safety stop.

These strategies somewhat mimic how decompression dives are executed; as a diver crosses the line from an aggressive recreational dive into a mild deco dive, usually the first obligation is an extended stop at 10 feet. As one gets further into required decompression, the initial stops get deeper and the shallow stops get longer.

Anyhow, try this and it should reduce any post-dive fatigue that's due to increased surface N2 or microbubbles. As far as other contributing factors, fitness definitely will help any fatigue after physical activity and staying warm should help as well. I wouldn't do any strenuous exercise immediately after diving though. I like to run in the morning before diving, but never right after.

One last thing, four dives/day is a lot to do on air IMO no matter how you manage your profiles, so if you are planning on doing liveaboards or doing that much diving daily, get a nitrox cert and still do the extended stops.

 

[tursiops]

There needs to be two studies, linked:

1. Decompression stress (bubble score) across a range of dive parameters (multi-day, repetitive dive, saw-tooth profiles, ascent strategies and nitrox use) to determine the sub-clinical DCI impacts of predictable diver behavior. This would produce knowledge that identified hi - med - lo range decompression stress dive behaviors/factors.

2. The impact of decompression stress (a range of bubble scores; hi - med - lo) upon perceived post-dive vitality and energy. The crux of this study would be to measure decompression stress versus fatigue.

As of now, the science of diving has focused only on what is necessary to prevent (tolerably reduce!) clinical DCS occurrence. In short, it keeps divers out of a chamber, but doesn't care to what extent they are 'zombified' after diving. It has largely ignored sub-clinical wellness and vitality. As more becomes known about the long-term health impacts of repeated / regular / routine exposure to decompression stress, that may change... (we might hope!).

Technical divers have long been aware of the existence of decompression stress. We use it as a 'yardstick' to determine what is optimal for us in our dive planning. Whether we feel 'fizzy', drowsy or vital after diving... is a clue as to whether we are getting our gradient factor settings, gas selection ascent profiles better or worse. But still, the emphasis is on keeping ourselves out of the chamber; not (often) on whether we are protecting ourselves against potential long-term medical consequences.

In contrast, recreational divers seem to have taken the issue of post-dive physical/mental dilapidation with a pinch of salt. It has become 'usual and expected'. The blame for post-dive sleepiness and lethargy goes on 'cold', or 'exertion' or 'fresh air'. Nobody gets a chamber ride, so nobody cares. They will.... if any of the current questions linking repetitive/routine decompression stress with brain lesions, osteonecrosis etc happen to be proven.

I think Devon Diver's posts in this thread do a good job of explaining the likely reason that nitrox use is often perceived as reducing post-dive fatigue. Putting it on a bumper sticker, a likely contributor to post dive fatigue is simply increased blood nitrogen levels upon surfacing. (He went into a lot more detail) Nitrox reduces those levels IF you do an identical profile as you would on air.

However, there's a good, simple way to reduce N2 levels on surfacing in recreational diving without using Nitrox, and that's by doing a very long safety stop and then proceeding to the surface very very slowly. Try it, you'll be surprised at how well it works. You might try 3 minutes at 15-20 ft, then an additional 7 minutes at 10-12 feet, then take a full minute to surface from 10 feet. If you have a computer, it probably has a N2 loading bar graph. Don't surface until you're in the 'green' segments of that bar graph. On repetitive dives, this will probably mean longer stops at 10-15 feet.

The deep stop idea and avoidance of up-down-up-down profiles are related to the formation of microbubbles in the blood. You might try reading more about this, but even if you don't fully understand it (I don't) the practical answer is easy to understand; manage your profile so that you start deepest and gradually work your way to shallow. If you are on a dive that has a deep 'square' profile, do a brief stop at approximately half your depth before proceeding to your safety stop.

These strategies somewhat mimic how decompression dives are executed; as a diver crosses the line from an aggressive recreational dive into a mild deco dive, usually the first obligation is an extended stop at 10 feet. As one gets further into required decompression, the initial stops get deeper and the shallow stops get longer.

Anyhow, try this and it should reduce any post-dive fatigue that's due to increased surface N2 or microbubbles. As far as other contributing factors, fitness definitely will help any fatigue after physical activity and staying warm should help as well. I wouldn't do any strenuous exercise immediately after diving though. I like to run in the morning before diving, but never right after.

One last thing, four dives/day is a lot to do on air IMO no matter how you manage your profiles, so if you are planning on doing liveaboards or doing that much diving daily, get a nitrox cert and still do the extended stops.

I agree completely with these two posts.
.
I have also noticed that on my deco dives, where I spend lots of time at 30-30-10 feet or whatever, often on high %O2 mixes, I do not feel fatigued afterwards. The nfatigue is only after multiple recreational air dives. So I expect the advice to take really kliobng safety stops, and maybe double ones (20 and 10 ft, for example), and very slow ascents is good advice.

 

[MXGratefulDiver]

Here's my take on the topic ... if you're feeling excessively fatigued after a day of diving, there are two main suspects. The first is simply that you're not used to the activity, and any activity you're not used to tends to make you feel tired. The second is that you're ascending too fast ... and the main culprit here is what you do after you complete your safety stop. Many divers will be religious about watching their ascent rate and doing their safety stop ... then as soon as the three minutes are up they take about 5 to 10 seconds to surface. That's WAY too fast ... at 30 feet per minute, it should take you a full 30 seconds to reach the surface after your safety stop. If you take less time than that, you're ascending too fast ... and at the point in the dive where it's most important not to do that. You're effectively "shaking the soda can" ... so you can expect some bubbling to occur, and that will make you feel fatigued.

Time your ascent after your safety stop. If it's less than 30 seconds, slow it down and pay attention to how it affects your fatigue level. Chances are this is where you'll make the most noticeable difference.

As for using nitrox, the main reason to use it is to extend your bottom time. On multiple dive days, it can be a good investment ... for most new divers, you'll be more limited by your available gas than you will by no-decompression limits, and nitrox will offer limited benefit for the added cost.

... Bob (Grateful Diver)

 

[Storker]

[many good points]

As for using nitrox, the main reason to use it is to extend your bottom time. On multiple dive days, it can be a good investment ... for most new divers, you'll be more limited by your available gas than you will by no-decompression limits, and nitrox will offer limited benefit for the added cost.

Well, for me - and quite a few of my regular buddies - the NDL on air and the min gas limit are pretty well correlated. For some of my buddies, it's definitely the NDL that limits their bottom time.

On nitrox, we basically only have to monitor our SPGs. To me, that's a win


--
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Typos are a feature, not a bug

 

[Bigd2722]

years ago I was talking to the owner of a 6 pack liveaboard. his experience was that an individual diving air was generally more tired than a nitrox diver after day 3 of a week long trip. I know this anecdotal, but it seems to make sense to me. I only dive nitrox unless it's not available.

 

[lerpy]

I find I feel a bit less fatigued on multi dive trips when I am using nitrox, but one off dives I am not sure that I notice a huge difference. As well now, I have become more, we will say aware of using nitrox on multi dive trips due to the O2 loading. I am very very new to this tech stuff, but when looking at O2 use in my course, we talked about the 24 hour O2 clock, and the risk of using say a 34% when say doing 5 dives a day for 5 days on a trip. I will ask others that know way more than I to clarify if I am remembering this correctly as I can not explain well, but it appeared to be a risk that often is not well outlined in recreational nitrox courses, the build up over time of O2 in your system, as on many vacation trips or live aboards you are not actually leaving enough time for proper off gassing before going back in the water for your next day of diving.

 

[MXGratefulDiver]

Well, for me - and quite a few of my regular buddies - the NDL on air and the min gas limit are pretty well correlated. For some of my buddies, it's definitely the NDL that limits their bottom time.

On nitrox, we basically only have to monitor our SPGs. To me, that's a win

Works for some ... but it depends on dive profile, tank size and consumption rate. For me, even on single dive days, I'll often go into deco long before I get low on gas ... even when using nitrox. It's common for me to finish a dive with more than 1000 psi left in the tank ...

... Bob (Grateful Diver)