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alkaline diet?

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Well-Known Member
Nov 7, 2001
hello freedivers, I have a doubt to share with.
When we are on static apnea it´s supposed that we suffer respiratory acidosis, and when on constant ballast or dynamic apnea we have to add metabolic acidosis. So we are supposed to be in a profound mixed acidosis while freediving. The acidosis will afecct our cardiac and skeletal muscle performance, and I think this will limit our apnea time. This has not been proved since most of the field experiments are non invasive and some uses subcutaneous pH-metry, but if we remember the periferal vasoconstriction this measure maybe isn´t too accurate. I know about a french experiment with japanese ama freedivers, but they don´t publicate any data about blood pH. My question is if we start a diet that put our blood pH in the normal superior level can we improve the apneic time?
Does anybody know something serious about this topic?
The Chemistry of Success

A while back I was investigating an alkaline diet for health reasons. I ended up buying a book called the "The Chemistry of Success", which lists six areas of chemical/biological balance which will improve your health/performance. The very first one was maintaining an appropriate acid/alkaline balance. The focus of the book was more for general health than for performance (or apnea) but the authors did quote some performance studies where athletes were given sodium or potassium bicarbonate right before a timed exercise to see if an alkaline body get improved times. The results were inconclusive, some studies did show some improvement, some did not.

The authors did think that keeping things alkaline would improve your recovery time after strenuous exercise, and your resistance to disease.

Oh, and this assumes you're like the majority of people that run on the acid side of the acid/alkaline balance (due to an acidic modern diet). If you're naturally alkaline none of this applies.

Then there are those that think this whole acid/alkaline is bunk given that your lungs can rid your body of acidosis quickly by respiration of CO2.

If you're interesting in playing around with your acid/alkaline balance I can give you a few pointers on what to try.

Hope this helps,
Balance better than base

A number of tricks have been tried over the years - e.g., carbohydrate loading, protein stacking, etc. - to enhance athletic performance, but none have stood the test of time. I'm not at all surprised to find that an alkaline diet produced inconsistent results - that is often an indication that there is no real beneficial effect rather than that there is some random, yet-to-be-discovered factor that magically makes it work.

As you well know, alkalosis is not healthy, so I would hesitate to try to push your body in that direction unless there is a medical reason to do so, i.e., a disease state that calls for it.

Acidosis induced by extreme exertion is not a disease state and the body has a marvelous mechanism for maintaining blood pH that was designed to handle physical exertion of all kinds (after all, sedentary life is a relatively recent phenomenon). Therefore, IMO, it makes more sense to emphasize a balanced diet and adequate intake of vitamins, minerals and micronutrients that assist your body's innate capacities rather than trying to anticipate its weaknesses and concoct a solution.
extreme apnea

Thank's Don for your information, but what I'm looking for, is a serious trial on this. I can work on my self but this will not prove it is useful. Anyway I will receive any pointers you want to give me.

I want to clarify my question to cjborgert, due to my profession I'm well aware of the problems of the acid-base status, I will never push my self to a metabolic alcalosis, because I know the deleterous effect that it has. I know the previous studies, but I want to know if there is a specific trial on freediving.
We know that after a hard exercise we develop a metabolic acidosis, and I agree with you that is not a disease, it's just physiological and transient.
When we are on 7 minutes of static apnea or below 50 meters of sea water, we are taking our body to the physiological limit and it's possible to be in a deep mixed acidosis. So, my question is if I keep the pH in the "normal superior level" (not in alkalemia) can I improve the performance in extreme apnea?, Any serious study can prove it?
Thank's for your answers
Frank Pernett
Alkaline diet

My friends and I tried the alkaline diet idea long ago. I also know of at least one swedish diver who tried it. Of course, if you want to modify your acid base status faster than changing your diet, all you really need to do is mix some sodium citrate and potassium citrate in the correct ratio (keep Na:K 3:1), and drink the weak solution (around 5% by mass). However, I don't recommend drinking electrolyte solutions, so please don't try it.

Either way, alkalinity causes problems. First of all, the Hb-O2 affinity is modified. The more alkaline you are, the more your Bohr effect will be reduced in the end of apnea. This can cause a premature blackout, not unlike hyperventilating. A very alkaline person is more likely to black out during packing also (again because Hb-O2 affinity is too high and other reasons). In short, acidic blood is very helpful in the end of apnea. Your body expects to be acidic, so don't fool it.

Actually, Peter and I, after long experiments, came up with a simple rule before deep diving. We often do a pre-dive static on the surface--at this point we are not particularly relaxed, nor do we do a big breathe up, so we don't expect big times. During our pre-dive surface static, we should get contractions around 2:05 to 3:00. If we make significantly more than 3:00 with no contractions, we are too alkaline and we risk a premature blackout during the dive. Diving when too alkaline feels like diving after hyperventilating, and physiologically it is quite similar. The symptoms are simple: some light-headedness on the final breath/and/or during packing, feeling great during the whole dive until the last 20m, when suddenly you feel like crap, you get uncomfortable-style contractions, and things tend to start fading in a hurry. On one such a dive, I had a small samba after only 2 contractions during the dive.

Alkalinity is not the only dietary issue, there are many more which we are experimenting with.

Eric Fattah
BC, Canada
Generally you will find that athletes at the top of their game (like Eric Fattah) are alkaline enough for top performance in whatever sport they specialize in. I figure that a certain amount of social darwinism is taking place - acidic individuals don't make it to the top echelon of sport.

But if you are not naturally endowed with an alkaline body, or you have the usual acidic reaction to the modern diet, you can tilt the odds in your favor by playing around with alkaline foods.

To make sure you don't go too far and become overly alkaline, you need to test your body pH while you make adjustments. A simple way to do that is to buy a bunch of pH strips that concentrate on the 6-8 pH range and test the rest pH (between meals) of your saliva. Apparently, as long as you haven't eaten recently the pH of your saliva will give you a good indication of the pH of the intercellular fluid in your body. The pH that you're shooting for is 7.5 . A pH of 8.0 is too much.

When I started playing around with alkaline foods my pH was around 6. When I got it up to 7.5 I noticed that my body felt better when doing aerobic exercise. Another thing I noticed was that my teeth felt healthier, and my breath fresher. When I was younger, I had bullet proof teeth. I went years without a dental visit and had no cavities. Some time while I was in college I started getting more plaque around my teeth and cavities. I also needed that occasional breath mint. I figured it was just a normal effect of aging. When I was a kid I noticed that adults had that noticeable "adult breath". When I got to college I had it too! But getting my pH to 7.5 got rid of the plaque around my teeth with the usual brushing I do. And I lost the "adult breath".

Whether the alkaline diet helps my performance or not, it seems to have obvious health benefits, so I'm going to keep it around 7.5 if I can. I figure if keeping my pH to 7.5 is helping my body fight bacteria in my gums, it must be helping with bacteria in other parts of my body. I don't consistently keep my pH to 7.5 due to other distractions in my life, but I don't have to use pH strips anymore - I can tell what my pH is by licking my teeth.

As Eric mentioned, a good way of getting your pH up is to use some kind of sodium/potassium combo. A quick way is to use sodium bicarbonate (baking soda), but you'll end up with too much sodium if you do this on a chronic basis. The easiest way I have found to alkalize my body is to use AlkaSeltzer Gold. Don't use regular AlkaSeltzer because it contains aspirin.

Hope this helps,
Weight of evidence

I would not quarrel with anyone's personal experiences with dietary changes, but I'm also interested in whether controlled studies have been performed and if so, what they indicate.

I checked out about a dozen recent papers on this subject published in peer-reveiwed medical and physiological journals. Although there were benefits observed in a few studies a decade ago, the recent studies suggest that alkalinizing the blood does not enhance athletic performance. However, freediving or apnea were not among the activities tested.

I'd be very interested to know of more studies that showed a benefit (please send me a reference list if you have one). If there is some identifiable difference between protocols that result in a benefit versus those that do not, it might help freedivers who are interested in enhancing performance through alkaline diets.
More research?

Thank´s everyone for your answers.
I like both point of view. To experiment with your self and to find well controlled trials to prove that idea.
The saliva pH can be altered by mouth infections, reflux and diet; did you ever try to test your urinary pH to be sure your in the right side? Althought the urinary pH doesn´t reflect either the arterial pH. As cjb noticed it actual trials on this issue shows opposite results, and no one involves freedivers. Unfortunately I didn´t find any trial on this issue.
Should We design a trial to prove it?
Thank´s for your opinion

Frank Pernett
"6 months in the lab can save you an afternoon in the library"


I was thinking that a systematic comparison of the various published studies might reveal some differences that folks can explore in their own search for an improved diet. -Using what others have already tried sometimes streamlines your experimentation.

I can send you the titles and abstracts from my search if you like. We could then choose the papers that look to be most relevant and I can retrieve them from a document delivery service that I use. Let me know.
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Reactions: fpernett
agree 100%

I agree with you, It's very useful to know the previous studies.
I'll like to see your search abstracts
And if you can get the full text document We can find if exist good evidence on this topic

Frank Pernett
Danger Danger

This is not a criticism of any of the contributors. Eric's post pointed addressed some of my concern already.

Anytime we start creating extremes in biochemistry we will produce unexpected effects and few of these are ever good. Acidosis-Alkalinity have effects throughout our bodies with far more of them in the neural systems. Taking your neurons to their homestatic limits is extremely dangerous. You can literally cause a systems crash. What governs our respiration and heart rate are our central and peripheral nervous systems. If you combine extreme dietary programs with extreme physical training programs you can cause permanent brain or organ damage, or die.

So please be cautious and remember that for some reason the whole nutritional area has a huge contingent of quacks who can be hard to distinguish from the real thing. People can take on a religous fervor for their dietary beliefs and nutritional gurus. Finally if you plan to experiment on yourself you will run into problems of determining the effect as it is impossible to do a double blind study on ourselves and single subject studies are next to worthless in this area.
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