I just started the level 1 half marathon plan. I noticed the long runs are by time. In the book, the plan was in miles. I have been doing low heart rate training since June and still have to walk quite a bit to stay in zone 2. I’m worried I won’t get enough miles on my feet since I don’t get very far in one hour :). Is it ok to follow the miles on my long run days?
Yes, can you go by miles (but you do have some long runs by miles coming up in your plan). I would not run longer than 20% of what the scheduled duration is. Anything beyond that has more risks than benefits on that plan. You have some 2 hour runs coming up as well as runs scheduled for 8 and 11 miles, and that should prepare you just fine for the HM, even if your HM will take more than 2 hours.