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

In simple terms, your muscles consist of two different kind of muscle fibers: Slow twitch and fast twitch fibers. Slow twitch fibers are very energy efficient, but produce less force. Fast twitch fibers use more energy, and produce more force.
The type of excercise will define what fibers will be used most, and those fibers will grow and multiply.

I recently saw a good video explaining the difference.