What are the sports cultures in America?

On the wall of the gymnasium, it doesn't say "work hard and win glory for our country", nor does it say "sweat more today and shed less tears tomorrow", nor does it say "work hard and strive for the upper reaches". But you see them fighting, sweating and struggling. They are not afraid of getting hurt. You can see that they didn't try to protect themselves at the moment of falling. They didn't put their elbows on the ground, nor did they hold their heads for any protection. They clung to the ball and tried to move forward, just to bring it forward a little bit in the second of falling.