Lactic acid

Wow. Complicated question. I’ll throw this out. Lactic acid on skeletal muscle might act differently than cardiac striated muscle. Also in the Face Of acidosis Oxygen more readily leaves the RBCs to the tissues. The heart and brain also can use lactic acid as fuel. This is a protective mechanism. No worries about doing what you are doing except don’t pass out, fall then hurt yourself.

To give a basic reply.. (you can do the googling required to get proper sources if you want)..

1) The heart muscle(s) has around 10x more mitochondria than any other muscle cell in the body, meaning that even during very intense workloads, the heart has about 10x the reserve capacity to continue functioning correctly even after lactic accumulation starts to happen in the heart muscle.

2) The heart has direct and 1st priority access to freshly oxygenated blood from the lungs: Literally all of you blood passes from lungs directly to the heart to heart. So even during extremely intense exercise far beyond your VO2-max, the heart is still always getting a massive volume of freshly oxygenated blood, and it's very unlikely to even become lactic in the first place. Under normal circumstances (healthy person) even at max BPM the heart is still mostly functioning aerobically. The body would crash well before the heart could suffer any kind of major acidosis.

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In terms of freediving. Yes of course hypoxia (in the lungs) does limit the oxygenation of the heart muscle. But again, thanks to the high density of mitochondria, the heart can continue to beat without suffering acidosis well beyond the point where every other muscle (and the brain) would fail before that could really happen.

Plus. During apnea the heart mostly stay at or below a resting BPM, so it's not working so hard anyway.

fabikp said:

Hi Nathan, many thanks for an in-depth explanation, now I know everything I need and can go on with my training without any worries. Pavel

Click to expand...

You’re talking about one of the three energy systems. Aerobic, ATP-PC and glycolytic. These vary on time under load in terms of how long you exercise for and the intensity. Picture a static muscle vs an exercising muscle, now picture the heart. One is a massive change, one is merely a varied rate. Interestingly your breatholding is what’s forcing last age as well, the lack of O2 will cause lactate to build up as a result of the glycolysis occurring to fuel your muscles. One warning though is to not overdo this as excessive lactate over prolonged days of lactate training can be dangerous.