Information About Isometric Holds

Hello everyone,

Do you guys have any good “bookmakered” article or threads of CT where he talks about isometrics ?
(What I mean is you take a weight and hold it in a certain position. For example bench press, you take a weight and hold it 5 cm over your chest for 10-20 seconds ).

To CT:
What’s the reason that I am able to perform well on them if my body is feeling drained. When you go to the gym and everything feels heavy , the isometrics are still feeling great, especially on the bench press!

Thanks in advance to everyone