Arnold Schwarzenegger said this quote

“ Being busy helping customers meant that I had no time to train the way I was used to, with an intense four-or five-hour workout each day. So I adopted the idea of training twice a day, two hours before work and two hours from seven to nine in the evening, when business slacked off and only the serious lifters were left. Split workouts seemed like an annoyance at first, but I realized I was onto something when I saw the results: I was concentrating better and recovering faster while grinding out longer and harder sets. On many days I would add a third training session at lunchtime. I'd isolate a body part that I thought was weak and give it thirty or forty minutes of my full attention, blasting twenty sets of calf raises, say, or one hundred triceps extensions. I did the same thing some nights after dinner, coming back to train for an hour at eleven o'clock. As I went to sleep in my snug little room, I'd often feel one or another muscle that I'd traumatized that day jumping and twitching-just a side effect of a successful workout and every pleasing, because I knew those fibers would now recover and grow. ”