Myoglobin and freediving

[trux]

I found a very interesting document about myoglobin in freediving on the website of Michael Nedwed. It is in German, but written quite comprehensively, so even if your German is not top, it may be worth of trying to read it. There is a lot of data and interesting information. You can try also the google translation, but I am not sure if it is usable in this case.

http://michael-n.info/artikel/Myoglobin.pdf

Basically the document addresses some overrated hopes of increasing myoglobin stores through training, and also shows that even significant increase of MB would not have a great impact on the overall performance. It also explains why MB level in blood is irrelevant, and does not correlate to MB level in muscles. High blood MB level does not really mean higher MB content in muscles, but rather over-training, injury, or disease.

Not sure if Michael is a DB member too, but in case he is, I hope he peeks in and posts more details here. Or perhaps he has an English version of the document somewhere too.

I have only a minor critique of the denial of the myoglobin boost - Michael writes, that even if we could increase MB levels in muscles significantly, it would bring only a few seconds, and because the availability of O2 bind to MB is rather local, its presence in muscles won't help with brain hypoxemia. He also speaks about the maximal discharge of MB being much less than 50%, because 50% can be achieved at anoxia (no oxygen available at all), while the level of hypoxia at freedivers is rather remote to anoxia.

Although I rather agree with most of the conclusions, I think Michael did not completely take in view the freediving response, and namely the vasoconstriction. In a deep DR state, muscles in extremities are in state rather close to anoxia, so the discharge of muscle myoglobin can be quite close to the ideal 50%. And then, especially at strong DR, high CO2 diving or at FRC, it is not the brain hypoxia, but muscle failure that is often the reason for aborting the dive. So in such cases, the higher myoglobin level in muscles could indeed help. Perhaps only a few seconds, but it helps in the worse final phase, and it can mean quite a few meters more. However, it still remains questionable whether it is possible to significantly increase the MB level in muscles through training, so I think Michael is rather right about the overrating of MB.

 

[trux]

BTW, there are many more interesting posts on Michael's blog, so keep the address in your bookmarks. I also added it to the Freediving News Feed on my website, so if you are subscribed through RSS, or visit it frequently, you will see headlines from Michael's blog there too.

http://www.michael-n.info/

 

[efattah]

I suppose Michael thinks that the myoglobin in marine mammals is useless as well ?

As you said Trux, under high vasoconstriction the myoglobin will delay muscle failure dramatically.

 

[trux]

I suppose Michael thinks that the myoglobin in marine mammals is useless as well ?

No, no, quite in contrary. And he also explains why. There is also a table with ratios between hemoglobin, myoglobin, and O2 stores directly in lungs at diverse marine mammals (plus a pinguin). The myoglobin part is quite small at humans, and the potential to increase it through training is questionable. The impact is therefore much smaller than at marine animals. Also the performance boost due to training induced myoglobine increase is put in doubts.

I may not agree with all what is written there entirely, but it is true that he shows quite interesting data, calculations, and mentions some details I was not aware of.

 

[wet]

"the availability of O2 bind to MB is rather local, its presence in muscles won't help with brain hypoxemia"

More importantly, it won't hurt.

Myoglobin in muscle, hemoglobin in blood, neuroglobin and cytoglobin in brain. With enough myoglobin in muscles for the ascent, oxygen is not needed from the core. I wonder if blubber holds oxygen compounds which muscles can tap when low, or perhaps a form of ketosis engages?

Recently scientists have found that skinny muscular adult humans, in addition to chubby human babies, have brown vascularised fat on the dorsal and ventral thorax which only visibly oxidizes (burns) when a person is chilled (clearly visible in thermal scans), while in warmed people or people with abundant white skin fat this is negligible (due to envelope of thermoinsulative non-vascularized white fat layer) and invisible on the thermal scan.

(note sea otter and walrus both slow dive for shallow benthics in cold water, only walrus has blubber).

[As typical, the study lacks physiological information about other hominoids, producing a relatively distorted image of human capabilities IMO.]

 

[Lil Dragonfly]

A marine biology professor once told me that marine mammals have myoglobin and humans don't. Lmao

 

[wet]

http://bio.research.ucsc.edu/people/williams/publications/pdfs/Williams et al 1997.pdf
See page 531 chart and 533 paragraph on comparing cheetahs, dogs, marine mammals in myoglobin. Not sure where precisely humans fit.

[chart note: "domestic dog" is probably greyhound. Guinea pigs have very unusual metabolism, like primates (apes, humans) they cannot make their own vitamin C, they must get it from their food, which is not typical for most mammals]

 

[trux]

A marine biology professor once told me that marine mammals have myoglobin and humans don't. Lmao

Yes, he was exagerating, but not so far from the truth. Seals and whales have around 70ml of myoglobin per kilogram of muscles, while humans only have around 8ml of it.

 

[trux]

See page 531 chart and 533 paragraph on comparing cheetahs, dogs, marine mammals in myoglobin. Not sure where precisely humans fit.

According to the initial doument, humans have almost ten times lower (more precisely 9.3 times lower) myoglobin content in muscles (8 ml/kg) than sperm whales (74.7 ml/kg), and 8.4 times lower than seals (69.3 ml/kg)

 

[wet]

Ivo, not meant to be picky, but is doument a French word, or did you mean document?

 

[trux]

Yes, just too many crumbs in my keyboard

 

[Fondueset]

you hae tha problem oo?

 

[Lil Dragonfly]

I accidentally spilled an entire bottle of ice cream sprinkles down my roommate's keyboard once!

 

[Fondueset]

With me it's sesame seeds.

 

[efattah]

What is being missed is that Emperor penguins are born with the same amount of myoglobin that humans have (8mg/g dry muscle). However, after 2-3 years of diving every day all day, their myoglobin increases through training to 50-75mg/g.

So there is every reason to believe that myoglobin can increase dramatically in humans. So rather than Michael speculating without evidence, he could do much better to simply measure the myoglobin in Davide Carrera or someone who spearfishes 5 hours a day. He would be shocked by the result. After all, how does he explain Davide Carrera's diving ability? Diving with only 7 litre lungs and doing 4 minute dives to 80-90m, where does all this oxygen come from? Davide is a small guy, certainly he can't have a huge blood volume either.

 

[trux]

Well, I do not know if they measured Davide, but they did studied myoglobine variations at diverse sportsmen. Actually you could find it out yourself relatively easily - just cut in some of Davide's muscles (best when he looks away), and look at the color. If the muscle is considerably darker than yours, then he likely has more myoglobin.

 

[hteas]

My understanding is that the high myoglobin concentration in marine mammal tissues is primarily for increasing the store of oxygen before a dive.
The scavenging of oxygen near the end of the dive might help for a few extra seconds, but would seem to set up a diver for a greater chance of blackout at the surface. When the diving reflex ends, the blood that would flood back to the core would have even lower oxygen concentration than now.
Anyone think this would be dangerous?