Maybe you guys kinda misunderstood me. Its not a question of a medical at all. My legs aren't in any pain or anything, and I don't have any such history of such kind. My question is more about flexibility, and how to improve leg strength. Maybe the title was very misleading, and I apologize. I can kick, low, mid range, and high, with technique, and with no pain. I can run well, move well, and healthy. I'm just having problems with flexibility, not being able to stretch how I use to, and not being able to hold my legs in a vertical position while I perform certain ab exercises.
I'm sorry for the confusion but its not a medical condition at all.