I've known people that have done these workouts before and it seemed to work for them. They didnt put on an inch, but my friend Don put on a good 1/4" doing one of those all day arm workouts. Its not actual new muscle growth, but an extreme stretching of the capillary bed from what i would gather. so it would give some cosmetic size. It probably only works once every few years, if even that i'd imagine. I've considered trying it before, but never got around to it. I remember my friend did light weight preacher curls, skull crushers, and dumbell curls, and did these exercises taking him about 10 mins, and then he would rest 30 mins, and go back at it again. All over the course of 8 hours. Before the workout he didn't lift for 2 days, and gave himself 3 days of recovery afterwards. He also packed in a **** storm of calories.