During my past 800m runs my hamstrings have locked up horribly in the last 200m of the race. I go through 400 in around 54 and end up dying to a 1:55 due to hamstrings locking up. My PR is 1:52 a race a year ago when my legs felt great. My only thinking is that my glutes are inactivated which leads to my hamstrings being overworked in the race. During workouts i can run 200's in 25, 26 and 400's 52,53 and feel great and relaxed when doing it but when I get to the race my hamstrings lock up very badly. My only thinking is that it may do to less warmup before the race and inactive glutes. Any thoughts?