Just ran 22km. Didn't feel so hard, but my heart rate is always 170-180 avg and cannot run faster than 6:45min/km. I wonder why is that. I run 3 times per week on evenings. I should probably try mornings again or add more walking to my training for the days of no running.
@rolle switching to morning runs for longer distances may definitely help, give it a try — I noticed my heart bears it better in the morning than in the evening (no specific stats unfortunately)