Does the body get better at removing nitrogen?

[CuzzA]

I don't have the answer but recall reading some studies that diving a lot, as in more than the average person and likely doing some impressive profiles, and/or breathing high partial pressures of o2 or mixed gasses has more long term detrimental effects than positive. Though I think in terms of this discussion for no stop recreational diving they aren't anything to really be concerned about.

That said, we could theorize that constant exposure to micro bubbles damaging cells and narrowing of airways over a long time might reduce a human's ability to off gas efficiently. Of course as mentioned, being a more experienced diver usually means you have better control over ascents and holding stops so that will help to off gas more efficiently. So perhaps the possible answer is yes, because you're becoming a better diver and eventually no as the long term effects of scuba diving take their toll. I think it's safe to say the older we get, the more conservative we should dive. That's likely because our bodies aren't as good as they once were.

The Long Term Effects Of Scuba Diving - AquaViews

Studies on the long term effects in both commercial and recreational scuba diving show that osteonecrosis and loss of hearing are the main concerns. Although over the past several years,medical literature and the lay press have suggested that there are potential chronic long-term detrimental effects of diving. This data implies that diving may produce subclinical damage to the brain, spinal cord, inner ear, retina, and the small airways of the lung. Other studies suggest significant decrement in pulmonary and cognitive functions. However, the dangers of these effects are contingent on the number of dives and depth of dives, history of decompression illness and a number of other factors regarding the divers health.

Long term deep diving can show consequences of decreased pulmonary function due to airway narrowing, dysbaric osteonecrosis and even suggest some neurological effects. The severity of the effects and the point at which they manifest themselves in deep divers appears to be established, but it is speculated that air bubbles will always travel to end organs, affecting them in some manner or another with prolonged diving.​

 

[Lorenzoid]

"Evidence"--no, I don't think it has been studied or we would have heard great debates over it here. But it's a great wild-a**ed hypothesis, and I'm guessing you're not the first to have thought of it. Not that you asked for anything beyond whether there is evidence, but a few things occur to me.

Anecdotally, we don't seem to hear divers who have racked up thousands of dives claim they are less prone to DCS than they used to be. Of course, as a person's number of dives increases, so does the person's age and, in some cases, physical fitness diminishes, which has been said to correlate with DCS, so maybe there are effects that tend to cancel each other out. Also, as people gain experience and age, they are often more conservative in their diving. A lot of variables.

I suppose anything is possible. My relatively crude understanding of the lungs' involvement in decompression--which is probably a good fit for the Basic Scuba forum--is that they act like a filter for bubbles. I can see your logic here, and it's certainly appealing. Maybe the lungs do adapt in some way. Of course, it's possible they could adapt in the opposite way--the lungs become LESS efficient at exchanging nitrogen. Lots of maybes, and again, this wasn't your question.

Then there's what has been called "sub-clinical" DCS that has been associated with symptoms such as fatigue. It's not well studied, either. It has been theorized to have something to do with the body's immune response system. So again, I suppose it's possible that the immune system could become more acclimated over time. Or conversely, more sensitized.

Anyway, maybe much of this has occurred to you, and what you're asking is specifically if there is evidence. I'm confident the answer is no.

 

[D_Fresh]

I would love to see an actual study on this, but I think it's mostly wishful thinking. However, I think that I've learned how to ameliorate and even avoid N2 issues over the years.

• Go slow. I have had students mention that I'm the laziest diver in the water. It helps with your SAC as well as feelings of being tired.
• Avoid undue stressors.
  • Remember the five rules of handling currents
    • Dodge
    • Dip
    • Dive
    • Duck
    • Dodge
  • Stay hydrated
  • Eat well
    
  • Get enough rest
  • Drink responsibly
    
  • Avoid temperature extremes
  • Avoid rushing by being prepared
• Avoid wild depth swings. Get neutral and avoid those saw-tooth dive profiles
• Ascend slowly. This can be a function of gas management and/or SAC.
• Do a full five minute safety stop. As long as I have enough air, nothing affects my after dive feels like getting in five minutes or longer on my safety stop. The closer I get to my NDL, the more important this becomes. FWIW, I always have enough air.
  
• Don't dive impaired! Learn to call your dive, even before you get out of bed!

Excellent post Chairman.


If you don't mind, I would like to point out that the above is what divers should be doing to lessen the amount of nitrogen absorbed and more properly release it from the body to avoid DCS. All of Chairman's points are grilled into OW students, but I believe they are also the first tidbits of knowledge that many dismiss after completing their cert.

With regards to the OP's question, these are (for lack of better words) skills and techniques, not the body acclimating/adapting. Becoming proficient and consistent in these skills will lead to longer bottom times, reduced fatigue, and (usually) less likelyhood for DCS symptoms.

 

[The Chairman]

Becoming proficient and consistent in these skills will lead to longer bottom times, reduced fatigue, and (usually) less likelyhood for DCS symptoms.

Indeed. You and only you, are in control of your diving. You might abdicate your role in making those decisions, but it's still all on you. There is no such thing as an 'undeserved hit', as that implies that some people deserve their DCS. You might not understand why you got bent and that's the problem. Embrace the fact that you are the only one fully responsible for your safety. This past trip to Fiji, I stepped into an unlit and unguarded drain, breaking both my tibia and fibia. Ouch. It's easy to blame everyone else, but I'm the one who stepped into it. In fact, I'm the only one who's had to deal with the pain and resultant lack of mobility. I didn't deserve this, but I still have to deal with the resultant consequences. How I wish I hadn't stepped into that drain.

 

[Akimbo]

Interesting question. Historically, dive tables were developed by exposing animals and navy divers in decompression chambers to theoretical calculated dive profiles. Animals were used repeatedly and human subjects were selected from the most experienced navy divers. Tests for both were conducted daily on relatively small numbers of individuals. The calculated tables were initially "refined" based on the experimental results and later from on fleet diving operation's DCS reports. This work began in the early 1900s. See US Navy Experimental Diving Unit for a US-centric overview.

Tables in recreational diving ranges were fairly stable and similar across several of the world's navies by the mid-1940s. Fast forward to the 1950 to the 1980s time frame where vast numbers of recreational divers were using various navy tables around the world. The occurrence of DCS was not significantly different between working navy divers and civilian Scuba divers. Granted, the meandering profile of Scuba divers tended to be more favorable than the square profiles of working navy divers, but the numbers were comparatively huge. This could argue that any physiological adaptation that may exist is not a statistically significant variable.

@Duke Dive Medicine may have some additional insights.

 

[Neilwood]

Indeed. You and only you, are in control of your diving. You might abdicate your role in making those decisions, but it's still all on you. There is no such thing as an 'undeserved hit', as that implies that some people deserve their DCS. You might not understand why you got bent and that's the problem. Embrace the fact that you are the only one fully responsible for your safety. This past trip to Fiji, I stepped into an unlit and unguarded drain, breaking both my tibia and fibia. Ouch. It's easy to blame everyone else, but I'm the one who stepped into it. In fact, I'm the only one who's had to deal with the pain and resultant lack of mobility. I didn't deserve this, but I still have to deal with the resultant consequences. How I wish I hadn't stepped into that drain.

Agreed - I hate the use of "undeserved hit".

I wish people used the term "unexplained" instead of "undeserved". There is always a reason for a DCS hit to happen - we might not ever know exactly why though.

 

[tursiops]

It’s a bit like asking if experienced skiers are more resistant to the force of gravity.

...only when underwater, and well-trimmed.

 

[uncfnp]

I seem to recall somewhere in my past reading a reference to the early pioneers of diving attempting to acclimate themselves to dives as they extended their range. A quick search found this...

Alert Diver | Acclimatization

 

[Duke Dive Medicine]

Another reference:
https://pdfs.semanticscholar.org/a7c7/1ca28561ed98a0999597f55873296637e636.pdf

From https://physoc.onlinelibrary.wiley.com/doi/full/10.1002/phy2.142:
"Habituation to stress decompression has been reported to decrease bubble formation (Pontier et al. 2009a) and protect from DCS in humans (Hagberg and Ornhagen 2003; Cameron et al. 2007) as well as in animal models (Su et al. 2004; Arieli et al. 2007). Postulated mechanisms include the depletion of complement proteins, thus preventing a massive activation of the complement system (Nyquist et al. 2007). Others studies propose the accumulation of protective factors such as early nonspecific stress markers HSP27 (Montcalm‐Smith et al. 2007) or HSP70 (Su et al. 2004)."

Best regards,
DDM

 

[TMHeimer]

This is just off the top of my head, but what about divers who have had a DCS hit possibly being more susceptible to more (possibly undeserved) hits?

I also think @TMHeimer has a good question about deep divers tolerating Narcosis better. But I think that might be more related to experience and awareness than to the body actually adapting. (Think like a heavy drinker who is drunk, but better at managing and compensating than a less experienced drinker.)

At any rate, as much as DCS had been studied, it still remains to be a very personalized topic. The "rules" are set to be as safe as possible for as many people as possible, but there will always be outliers in the data....

Regarding being more susceptible to DCS after having a hit... Someone once said that if you freeze a body part one time, that part is more likely to freeze again. I froze my nose about 30 years ago walking in the wind at -20C. It hasn't froze since.