Today's training calender had a 90-minute run planned with 4-5 all-out sprints at the middle of the run followed but some slow recovery. The plan says to complete the run at Zone 2- Zone 3 heart rate zones. I feel that is way too fast for workouts over about 50 minutes long so I waffled a little bit with the pace this morning. The first 4 miles were in the Z2-Z3 but after that, I dropped to Z1 until the last two miles that I again hit at Z2-Z3. After doing a Marathon in October I am more and more convinced that all my runs over an hour-long should be in the Z1 heart rate zone. I keep second-guessing my conclusion on this one though.