Went to my third BJJ class last night and we worked on escaping the guard into side control. When we got to the part of standing up to break guard then stack your opponent to get into side control I just could not stand myself up. Guy I was with is 250 and has tree trunks for legs wrapped around me. I would get partially up then my leg would just give out and i would fall on my ass. by the time I got home my hip was so sore I could barely walk. So far I'm loving jiu jitsu and already feeling better and lost 5lbs. Anyone else have this problem when starting or still have it. What exercises if any should I do to work on strengthening my legs or should I just let them strengthen from training? Thanks!