here is my deal, i have a huge problem with lactate threshold. i have never built a base before and i am just finishing my second year of highschool. my prs are as follows.
400: 53.02 800: 2:01.1 1600: 4:26.2 3200: 10:14 5000xc: 16:33
the problem is that I double poorly in races and get worse as distances go up past 1600. when i try to work on my lactate threshold during my base phase once a week the results are terrible. i can hardly run 4 miles at 5:55 pace and it is very hard for me. my normal runs are done at 7 minute pace and im never overly fatigued. what is my problem and how can i fix my overly weak lactate threshold.?