Im a Sophomore and have been running for around 4 years now. I am a 4:50 miler and 17:30 5k runner. For quite some time now I have always run my easy runs at a pace I have thought to be easy, but obviously not "to" easy. I have noticed that whenever I make a conscious effort to push the pace on an easy run I feel horrible the next day. I recently however began to look into Jack Daniels VDOT charts, and noticed that for someone of my fitness level, he assigns an "easy" pace in the low to mid 4:00/km pace. I then looked at the heart rate zone he assigns for an easy run, and noticed that if I ever run at his prescribed VDOT "easy pace" my heart rate would escalate way above that heart rate zone. Has anyone else found this discrepancy, and what would the final verdict be on this issue?