I knew a guy that did holds. There's this one old timer that loves his nipple t's and his headband, wears them everytime. I once saw him sitting sideways on a flat bench, doing forced-concentration curls with an 85lb dumbell! He did sets of 6 forced reps, than once finished, he'd get some molmentum going like how you would throw a discus, then he'd swing the dumbell up over his head with the assistance of his other hand, than preceed to hold it there with one arm for a count of 30. And yes, he did count out loud...
