I have been learning guitar since 4 years or so,but the problem that still bothers me is the playing of barre chords.I can play them clearly with every string sounding correct but the problem is that i can not hold it for long.
I do release pressure for some fraction of second and then grab the fretboard again to relax sometimes. But after some time finally my left hand feels like exhausted and muscles feels like locked or cannot move properly.it gets normal after relaxing for some time.But how to overcome this problem?
I need to play them as longer as possible,if not hours then atleast half an hour,right now i can only do it upto 2-3mins!How to improve my left hand strength?
Your problem i think is your barre. You should play with the side of your finger to reduce the amount of pressure needed to barre and thus you can hold the barre longer. Also try holding that shape and moving it up and down the fretboard without changing the shape.
You've got the right idea with the "relax and regrab" method, that's how almost everyone plays barres. Aside from just keeping up regular practice, make sure your left wrist is straight and that you're not using too much pressure.