Reduced ventilation a sign of fitness

Something that I’ve always used to measure effort is breath rate (ventilation).

When I first started training I noticed that it wouldn’t take much of an effort to get a high/fast/quick breathing rate. However, after 2.5+ years of structured training, I can now do VO2 work with a heart rate at 90% of max and still have very controlled breathing. It’s not until I hit ~95% does my breathing rate truly start to increase.

Has anyone else noticed this? Also, does breathing rate have any correlation to VO2max (oxygen uptake) or are they not related in any way? In otherwords, just because one isn’t breathing hard does not mean that they are not hitting peak VO2max?

PEZ Cycling published an article a while back that talked about as aerobic endurance increases there is a reduction in submaximal ventilation.