Pushing exercise intensity beyond the body's capacity to supply nutrients and oxygen to mitochondria triggers an adaptation to increase mitochondrial density.

“when you're pushing beyond the capacity of your your your body's ability to bring nutrients and oxygen to the mitochondria to be oxidized for energy and you start going into that you know zone three zone four where you're using glucose and producing lactate as a byproduct they you're at up your body is going oh I need to increase I need to increase my mitochondrial density so that I can start using my mitochondria right it's an adaptation it's a response to that stressor”