Last week during my soccer game i pulled my hamstring pretty severly. This happened while i was just running quickly in a straight line, no wierd movements of any sort. I have never experienced any type of hamstring problems in the past and was wondering if this could of been caused by an imbalance in my muscles. I have recently been doing a lot of deadlifts and squats. Most noticeably ive added deadlifts to my workout and have been able to increase from 70-80lbs to 225lbs. I weight a mere 150lbs. As far as quadriceps go i havent really been targeting them. Is this a case of imbalance or just a simple injury?