Ok, so I've been running for a while, not as long as some of you old people who have been running since before I was born, but since the sixth grade and I'm now entering my 4 year of college, running for a D1 university. I have a pretty good knowledge of basic training and have read quite a bit on heart rate training. I have recently returned to running after having to take 10 weeks off due to a stress reaction on my left tibia. My come back has been slow, partly due to lingering shin splints in the area of the original stress reaction, MRI has proven the bone is completely healed. Anyway, so I've been keeping the mileage fairly low, but running at 6:30 to 6:10 per mile and feeling pretty easy doing it. I've been doing a lot of biking to make up for the lack of running, anywhere from 140 to 200 miles per week, with a heartrate monitor keeping me at 60 to 70 percent of my max heartrate. I usually don't bother wearing the heart rate monitor when I run, it tells me I'm running to fast all the time, but today I put it on for kicks and giggles and ran 5 miles at my usual 6:30 to 6:10 pace, again feeling relaxed. Final result on the from the heart rate monitor says I averaged 170bpm for the run, which is like 86% of my max. Isn't 86% tempo effort? But in no way did this run feel like a tempo run. SO what's the deal? Am I running tempo everyday according to my heart, but my legs feel like I'm out on brisk run? What's this gonna do to my overall training, am I not getting in a proper base because I'm training too hard, even though it doesn't feel like it?