The comments bridge these gaps. Production of lactic acid allows for the production of ATP in the absence of oxygen. It’s like a buffer for peak loads. The h

The comments bridge these gaps. Production of lactic acid allows for the production of ATP in the absence of oxygen. It’s like a buffer for peak loads. The heart’s load is heavy, but relatively steady. It doesn’t have the ability to have peaks in output. It also can’t afford to not be supplied with a constant supply of lot of oxygen to feed the mitochondria. As a bit of a side rant: biology is complicated, that doesn’t mean good work hasn’t been done. I notice many people discredit the field of biology, but eventually make fools of themselves when talking about it. https://www.reddit.com/r/askscience/comments/fm2z8x/if_a_heart_is_a_muscle_why_doesnt_it_ever_get/fl269v4 https://www.reddit.com/r/askscience/comments/fm2z8x/if_a_hea...