The rivalry between Karasuno and Shiratorizawa pushes both teams to improve by constantly challenging each other to perform at their best. Karasuno is motivated to rise up and surpass Shiratorizawa's strong team, while Shiratorizawa aims to maintain their dominance and not be overtaken by Karasuno. This competitive dynamic drives both teams to push their limits, work harder, and constantly strive for improvement in order to outperform each other.