Cross climbing, or zigzagging, reduces muscle strain and energy use on steep stairs. Instead of battling gravity head on, moving at an angle spreads the effort over a longer distance, making each step easier similar to sliding a heavy load up a ramp rather than lifting it directly. . Credit: unknown All rights and credits reserved to the respective owners. This video is for educational purposes only. Dm for Removal . I promise you won't regret following us @explaining.astrophysics ❤ #donkey #phy