Q. What is the correct way of standing under the shower when doing nine kabbim?
A. Mishna Berura (88: 4) quoting Mateh Efraim maintains that when tisha kabim water are poured over someone, he should stand straight with his two hands loose and placed close to his heart, so that the water lands on his chest and also his hands.
Horav Shlomo Miller’s Shlit’a opinion is that when standing under the shower, it may be more effective to stand straight and have his hands down, while the water pours over his head and all over his body.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit’a