I just completed week 8 today but I've found for the last few runs my legs are tiring long before I'm getting out of breath. They feel really heavy - especially my quads.
In a weird way I kind of miss that exhausted out of breath feeling from the earlier weeks! It felt like I was really pushing myself aerobically which gave me that runners high afterwards!
Does anyone have any tips to help this? I've been stretching before runs and strength training twice a week - squats, deadlifts etc and I usually have two days off a week.