When training anaerobic exercise over a period of time, what physiologically is changing in your muscles that causes imroovement?

Question

I have been working on improving my health. I read about glucose, ATP, oxygen delivery etc. But when I am cross training and pushing myself, what is happening in my muscles? Do you grow more capillaries to deliver more oxygen to clear waste? Lactate forms, and exercising with lactate present improves muscle “tolerance” to it. But again, what is improving? Does your body produce more enzymes?

Edit: I want to differentiate the training I am talking about versus traditional “over loading” weight lifting (muscles get bigger)

In: 163

Answer 1

So another part of doing aerobic exercise is that your resting heart rate will decrease because your body becomes more “efficient,” at receiving oxygen from your blood. This is because your body increases the amount of capillaries in your body (when oxygen is diffused from the blood into your body, and the CO2 from the body is diffused into the blood(where it is then taken to the lungs to exhale the CO2 and inhale oxygen))
I have a bachelors in Exercise Science btw