Every great bodybuilding practiced a posing routine. That's isometrics basically. How come they didn't overtrain by doing weights plus all the poses and flexing?
Also do you think isometrics with weights is better for adding muscle size that ISOs without weights and just your body and solid objects?
The guys whose used jail bars to gain muscle was all they had, but do you think it was a gift for them to discover that weights are a hindrance and your body and some solid objects is all you need back in that day. Or do you think if those guys had weights back then they could have made better gains using ISOs?