Perfect Tactics - English Team

[Abu]

dind't your player will injured if you put the maximum intensity during the training?
i already tried power training but end up with injured player and green booster problem..
can you teach me how to get extra green booster and that injured player problem?
do you train the whole squad with power train or just an individual player?
my current level is 5 now..

1 more thing i want to ask why my player perform very poor?
when i in lvl 4 they always get 7 to 9 rating but in lvl 5 they only get 4 and the highest is 6!
resulting alot of mistakes during gameplay..