"Dynamic Tension" is the name Charles Atlas gave to the system of physical exercises that he first popularized in the 1920s.
Dynamic Tension exercises are not merely isometrics, since they call for movement.
[1] After being bullied as a child, Charles Atlas joined the YMCA and began to do numerous exercise routines.
There were many other "isometric" courses available at the time, and sales took off only after Atlas used an advertisement depicting a bully kicking sand in a weakling's face.
[2] Some other notable users of this method include Joe DiMaggio, Max Baer, Rocky Marciano, Joe Louis, Robert Ripley and Alan Wells.