Hi! I’m training to hopefully do mountain running some day…I’m trying to build an aerobic base and wanted to check in here because I think I might be messing something up.

After running for about 2 months (20-25 miles a week, every fourth week half that) my pace at the same heartrate has slowed significantly. I started out around 9 min/mi, now I’m around 12? I also took a full week off last week and while I feel fine I keep getting slower…Graph attached. I’m keeping an average of ~130-135 bpm as I took a lab test which showed my zone 2 at 140bpm. Is this normal, weird, or who cares?