You know, I always considered Michael as very skinny man. Well, he obviously was really thin during most of his lifetime. I bet, he could never done many pushups or pull-ups, he wasn't a muscle type. But recently I found this picture, where Michael holds Bigi with his one hand! And according to his face, it's not really difficult for him. If he could easily lift 60-65 lbs with one of his hand, then he actually wasn't really weak as he seemed to be! Moreover, this picture was taken, when he physicallly was weaker than ever! That means that during 90s he could be even stronger! I bet during Invincible era he could easily lift cars Anyway, also lets not forget Earth Song performances, when Michael could bend himself down on a hight altitude! So, maybe Michael had never gone to gym, he never tried to pump muscles, but he definately had really strong body, especially hands. Maybe it's all about genetics