Hi, I am doing an assignment on long term effects of exercise looking at energy systems and I was taught that aerobic and anaerobic enzymes involved in the production of ATP became more efficient at their job. I understand that there is an increase in the number of enzymes and Mitochondria but my tutor nor my research can find an answer as to why these enzymes become more efficient? What happens to them to make them more efficient? Or have I been mislead and they don't become more efficient they just simply increase in quantity?
Any theories or relevant studies would be appreciated.

This isn't really my area of expertise but I'd be more tempted to go with the explanation that the number of enzymes increases and hence the metabolic efficiency increases rather than the efficiency of each individual enzyme increases.