First, ensure that athletes will not be affected in the morning or afternoon. In fact, all competitions are directional. If the sun shines on a player during the daytime game, then the player must be at a disadvantage and his vision will be greatly affected. Therefore, in order to ensure that both players will not be affected by the environment, the north-south orientation is the most reasonable. Because the earth rotates from west to east, that's why the sun rises in the east in the morning and sets in the west at night.
If the stadium is north-south, the sun will shine from the east in the morning, which will have less influence on the athletes, and the sun will not affect the athletes in the afternoon. The sun shines around the athletes. As long as it doesn't shine directly on the athletes, it won't have much influence on the athletes' sight, and the side illumination is the same for both sides, which will be fairer.
Secondly, to ensure that the spectators of the stadium can better watch the north-south orientation of the stadium, then there will be more seats in the east-west orientation of the stadium, and the spectators can have a better vision and a broader and more balanced vision when watching the game. There will be no situation that the audience on one side can't see the other side clearly. Generally, the east and west sides of the gymnasium will be slightly higher, so that the audience's vision will be wider and will not be blocked by the goal or other buildings.
Although the audience usually watches the game in the east-west direction, if there is the sun, the eaves of the stadium are partially blocked and the athletes run in the north-south direction, which can make the audience see more intuitively and clearly. If athletes are still moving in the east-west direction, they will not see the situation clearly. So the design of the stadium is reasonable.