I know alot of you will just say "why don't you go run one and find out" but I'm in the base phase and just want to know how much my aerobic fitness has improved. Today I did a threshold workout of 3x1.4 miles with 2 minutes recovery in 8:21, 8:17, and 8:05. As you can see I wasn't straining to complete this workout as I negative splitted each rep. I didn't taper or anything for this workout and actually did a pretty hard weight session the yesterday. I have been running about 45ish miles a week and am a middle distance (800m) runner, so I above average speed. Thanks to all who answer seriously.