here's my explanation for why Dorian's waist seems to change sizes. He naturally has a wider waist and thicker obliques than Ronnie. However, Dorian was much better at posing. He would flex his transverse abdominals to tighten his midsection. Watch the 96 Mr. Olympia video at the end. Right before he hits an abs-and-thighs, he throws his arms over his head and makes his waist shrink. Then he contracts his rectus abdominis. Ronnie doesn't have such mastery over his posing. When he hits the abs-and-thighs, he seems to flex his abs and push his obliques out even more.
