I’m a senior in high school and my 5k PR is 17:22. I run about 50-55 mpw. During my races this year I feel like i have way too much left in the tank but i can’t get myself to use it for some reason. My heart rate for most races doesn’t go above 170. yesterday i ran 17:23 and my Max heart rate was 166 during the race. Never went above that. During long runs of like 12 miles at 6:30 and tempos i’ll go to like 180-195 for a good portion of the workout. Do I need to warmup better or what? I think I can run faster based on my heart rate during races. What do you guys think?