I think I am in trouble as I tend to take a sip of coffee between breaths...

As far as I know meat and carbs increase blood acidity and veggies lower acidity

Ryan.Burmester wrote:
Another very good tip which Jules swore by and especialy when diving a few days in a row is to smash food and hydrate as soon as possible after the dive this will let your body repair alot quicker for the next days diving.

Also fully agree, if i go on a dive trip I eat loads of good food after my dive and wash it down some of coatsmans recovery aid. I swear by that stuff after a heavy days diving where you know you got to do it all again the next day.

Blood Ph is important to a diver because alkaline blood does different things with o2 compared with acidic blood.

We remember from school that limestone caves are formed by rainwater mixing with Co2 to form carbonic acid. This weak dissolves limestone and forms the caves over time.

So its easy to remember that the higher your Co2, the higher your acidity and the converse is obviously true.

While diet can play a role in blood Ph, the strongest and most flexible variable of your blood Ph is your breathe-up.

This is a bit off topic but it relegates dietary effects on blood Ph to second or even third place in the Ph rankings because of its powerful effect on ambient Ph.

As we breathe up we do not increase our blood oxygen by much more than 1 %. During tests at Ellis park conducted by Dr Mark in 2003 we found that the most agressive of breathe ups ie extreme hyperventilation, only increased 02 from 98 to 99 % as measured with an oxymeter.

What it did do though, was blow off excessive amounts of Co2, and our blood turned very alkaline in a short space of time.

Alkaline blood is very receptive to o2 and increases the efficiency of haemoglobin to uptake o2. What alkaline blood is not good at doing though, is letting go of it.
Alkaline blood ph also constricts the blood vessels in the brain so the flow is reduced by that mechanism too.
This is why you can pass out prematurely having good levels of o2 in the blood. This is the physiological reason why hyperventilation is generally not a good thing.

Acidic blood levels encourage haemoglobin to dissociate o2 readily and dialate blood vessels in the brain increasing blood flow through the brain and giving off the stored o2. A person blacking out with low o2 in the blood will inevitably be in a state of respiratory acidosis.

So here in lies the paradox. We want to be alkaline to maximise the take up o2 but we want it to dissociate from our haemoglobin efficiently when it matters most - towards the end of an apnoea. This implies a change in blood Ph from alkaline at the start of a breath-hold across Ph neutral, to acidic at the end stages of a dive.

We can achieve this by balancing our breathe up and the physical exertion we exercise during the dive.

While the extreme techiques I mention here next are mostly relevant to one big competition dive they can be toned down to multiple dives as in spearing and it all boils down to knowing your diving physiology and knowing your body.

Breathing up blows off Co2. Physical exertion builds it up. How do we balance it such that we cross Ph nuetral from alkaline to acid if we dont have a scale to measure the Ph ?

Each day your blood Ph is a bit different to other days. Someone earlier mentioned some days breath hold is easy and others its hard. If we could find the alkaline limit of our blood we could tailor our breath up to position our starting Ph to suit the dive.

I did a 45 minute controlled breath up with "hyperventliations" for competition dives to find out where I was on the Ph scale on that day. From experience I knew the signs of hyperventilation. First my fingertips would tingle. If I persisted my tongue would begin to tingle. If I persisted still further, my stomach / diaphragm would begin to tingle and palpate. If I dove like this I wouldn't reach the bottom conscious.

It was most important for me to know when my fingertips began to tingle as through experimantation and experience, this would place me on a recognisable point on the Ph scale. Depending when this happened during my 45 minute preparation - during which I did different things on a strict time based schedule- I would alter my breathup by breathing slower, hold my breath, breathe less deeply or perhaps even flick and flex my hands and feet to build Co2 back up to a point on the 'scale' such that at dive time, my Ph was at an intended level, calculated to reach neutral at the turn of the dive.

After the turn, I would recognise physiological signals that may require me to gain more Co2 and have my blood turn acidic, and give up the o2 it was holding on to for me.

If I got it right, at the turn I would give a measured series of big full effort kicks. Co2 would build up rapidly and I would feel a warm flush as my air came back by the process i have mentioned above.
This quenched any urge to breathe and depending on the depth of the dive, I would time if and when to do this. This also activated an anaerobic process which preserved even more o2 in the blood for consciousness, but I will talk about that at a later time.
To be sure I would always be accelerating through the death zone from 10m down to the surface. I always surfaced a bit tired but full of air.

This approach is unsustainable on multiple spearfishing dives but it does give some insight and understanding to the real purpose and mechanisms of manipulating blood Ph.

Having said that, this technique has some place even in multiple deep dives for a well conditioned diver with strong, lactic acid tolerant legs.

regards
Greg.

wow Greg

Thanks mate, very informative.

Hi Greg,

Welcome to the forum and thank you for a very insightful contribution. Whilst I've heard and read about blood ph levels, this is the first explanation that actually makes sense. We look forward to more contributions from you on the subject.

Thnx Greg for that great piece. Bump a Karma for it.

(Totally off the subject) … FYI

For those who don’t know Greg (skindiver), Greg Monto Lewis is a world class freediver and represented South Africa in the AIDA World Freediving Championships a couple of yearsssss ago. He was also one of the founder members of FSA (Freediving South Africa) which was the organization sanctioned in South Africa to host the Freediving SA’s.

In my opinion Greg is one of the top and knowledgeable freedivers in South Africa with a few SA freediving records to his credit, I have loads of respect for him. What raises him head and shoulders above all other knowledgeable freedivers in SA, is his willingness to share his knowledge without charging people for it… So when Greg speaks, you sit, listen and learn.