Those old books are interesting to look through, and you may find some useful exercises in them, but weights are better in pretty much every way when it comes to developing strength.
I think there was a lawsuit where a barbell company sued Charles Atlas. Remember him? He was the whole dynamic tension for bodybuilding thing. His ads had the 95lb weakling getting sand kicked in his face on the beach, and then he did some isometric exercises and came back as a stud and got the girl. Anyway, supposedly the lawsuit went something like this:
Charles Atlas: I got my size and strength from my dynamic tension program
Barbell Company: No you didn't, you got it from using our barbells.
Charles Atlas: No, I only use barbells to test my progress.
Barbell Company: And how often do you test your progress?
Charles Atlas: About 3 times a week.
I don't remember where I read that, tho, but for some reason that story is stuck in my head.
Anyway, dynamic tension and flexing and stuff has it's place, but it's place is probably about 1-2% of a workout, so basically don't worry about it. Weights are the best way.
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