I recall seeing a TMuscle article referring to abs as being heavy on fast-twitch fibers. I’d guess the statement “there isn’t really a way to know if a muscle is fast twitch or not” came with some unvoiced qualifier like “without cutting the muscle up and looking inside”.
The are 45 mph couch potatoes. I had one jump 26 feet, in the mud I might add. I dropped the tailgate down in my pickup once and it had a lift kit on it. He decided to jump over the rear wheels instead and into the bed of the truck.
The other side, sometimes they won’t even get up to answer the door. They are not watchdogs by any means. In fact you have to protect them. I absolutely love them. Plus I don’t catch near the shit I did when I was rescuing Pit Bulls.