Use of Nitrox for increased activity?

[beperkins]

Dear Dr. Deco,
My local dive club is hosting an "Amazing Race" style dive competition in a freshwater quarry with a max depth of 25 ft for about 50 min. I know I do not need Nitrox for NDL reasons. As this is a timed event I was wondering if there would be any benefit to using a 40% nitrox mixture to increase my speed and endurance for the competition? I am in good shape and have no problem keeping up a good pace, but if there would be an advantage; every little bit helps. Would an increase in the Oxygen level help your muscles, maybe reduce that feeling of fatigue or burning that comes with heavy exercise?

Thanks

Ben

 

[Dr Deco]

Hello beperkins:

No. Breathing oxygen will not help your performance. Performance is a function of muscles. That in turn depends on capillary density and number of mitochondria per cell. [I am sure there is a lot more.] Long-term training can modify these but not an increase in oxygen for a short time.

Additionally, people feel “out of breath” because of a build up of carbon dioxide, not an oxygen lack. This is not changed by oxygen breathing.

It was a good thought, though.


Dr Deco :doctor:

 

[cutlass]

...
Would an increase in the Oxygen level help your muscles, maybe reduce that feeling of fatigue or burning that comes with heavy exercise?
...

As for this piece, one of the more popular theories of post-exercise muscle pain is laid on accumulation of lactic acids; i.e. metabolic waste. Although it is valid to say that excess acidity is "blown off" by breathing mechanisms related to O2 and CO2 exchange, accumulation of acids is more associated with decreased muscle strength rather than pain. Pain is more tied to the body's natural responses (inflammatory) to mechanical damage of muscle tissue.

In fact, a colleague once mentioned a couple of studies which showed there's less to this lactic acid theory than popularly believed. Unfortunately, I don't have the citations but one was a rat model study and showed a disconnection between levels of lactic acid and pain (pain in terms of muscle damage which was evaluated in terms of levels of a certain muscle breakdown enzyme). The second study found that hyperbaric oxygen therapy was ineffective for treating post-exercise muscle injury.

 

[fppf]

I don't know, I see an awfull lot of NFL players on the bench sucking O's

I also personally feel less tired after scrubing a hull with left over Nitrox from a previous dive than with air.

But I'm not a Doc.

 

[cutlass]

I don't know, I see an awfull lot of NFL players on the bench sucking O's

I also personally feel less tired after scrubing a hull with left over Nitrox from a previous dive than with air.

But I'm not a Doc.

I agree that in terms of fatigued feelings and muscular weakness, supplemental O2 is beneficial -- this is a somewhat related post: linky But there seems to be no role for supplemental O2 in relieving post-exercise muscular pain and here, I'm guilty of lumping the term "burning" into the class of "pain". Someone else may have a different interpretation of the "burn".

 

[String]

I don't know, I see an awfull lot of NFL players on the bench sucking O's

and all the controlled studies into any effects have come out negative. Just because they do it doesn't mean it actually has any real world effect.

Anyway nitrox is not going to help anything. If it were oxygen being the limiting factor to endurance it would. However it isnt. The body doesnt work like that. You dont need all the oxygen in normal air, especially at hyperbaric pressures. So increasing that oxygen intake just means there is more oxygen you dont actually need which is just exhaled immediately.

(plus at the extreme end doing strenuous work underwater at high ppO2s increase the potential for an O2 hit)

 

[miketsp]

Hello beperkins:

No. Breathing oxygen will not help your performance. Performance is a function of muscles. That in turn depends on capillary density and number of mitochondria per cell. [I am sure there is a lot more.] Long-term training can modify these but not an increase in oxygen for a short time.

Additionally, people feel “out of breath” because of a build up of carbon dioxide, not an oxygen lack. This is not changed by oxygen breathing.

It was a good thought, though.


Dr Deco :doctor:

The only "serious" study I ever saw states
"The results of the study provide strong support for the positive effects of hyperoxia on the performance of firefighters, and suggest the need for further research."

Note that the "benefits" only appear at high workloads.

 

[Dr Deco]

Hello beperkins:

I read the very interesting report posted by miketsp. This indicates the effect of hyperoxia on trained individuals in very strenuous activities. In individuals with high capillary density and mitochondrial density [i.e., trained individuals], increased oxygen does make a difference. Some references are below.

If you are in the “well fit” group – and you indicate that you are – the hyperoxia might be just the ticket for that “edge.” Twenty years ago, I ran from my house to Providence Medical Center, a distance of six miles each way. [I even made a couple of newspaper articles.] I would have some difficulty walking that distance today. Oh, fleeting glory. Hyperoxia would not do much for me!


Dr Deco :doctor:

The next class in Decompression Physiology for 2008 is November 15 - 16.
This class is at the USC campus in Los Angeles.
Advanced Decompression Physiology Seminar Information


References

Bannister RG, Cunningham DJ. The effects on the respiration and
performance during exercise of adding oxygen to the inspired air.
J Physiol 125: 118–137, 1954.

Welch HG. Hyperoxia and human performance: a brief review. Med Sci
Sports Exerc 14: 253–262, 1982.

Welch HG. Effects of hypoxia and hyperoxia on human performance.
Exerc Sport Sci Rev 15: 191–221, 1987.

Plet J, Pedersen PK, Jensen FB, Hansen JK. Increased working capacity
with hyperoxia in humans. Eur J Appl Physiol Occup Physiol 65:
171–177, 1992.

 

[gsk3]

As far as the OP's question, hemoglobin (the iron-bound molecule that carries oxygen in the blood) is very quickly saturated with O2 at the levels of O2 found in the lungs while breathing air. Nitrox shouldn't make much of a difference, unless you're really breathing insanely hard, which may be the reason that highly trained individuals potentially see benefits if that study posted earlier is correct.

 

[don Francisco]

From experience with cycling performance, I can tell you that extra oxygen delivered to the lungs will not get to the cells any faster. In a healthy person blood hemoglobin tends to be very close to 100% saturated with oxygen as it leaves the lungs and goes out throughout the body, and therefore has little or no additional capacity.

In order to deliver more oxygen to your muscles you need to increase the delivery capacity; acheived through excercise which builds up the network of capillaries and the pumping efficiency of the heart. Cyclists when looking to increase capacity illegally, "blood doped" a process wherein red blood cells were removed over time, stored and re-injected into the bloodstream before an event in order to have greater amount than normal hemoglobin levels, and increased oxygen delivery capacity.

In short, when looking for improved performance don't worry about the oxygen supply, but the delivery capacity.