Australian Rules Football is a fast game played on a big pitch in a hot climate.
Rugby (Union and League) and Football (Soccer) are winter sports intended to be played in British drizzle and sleet. Hence the long sleeves and rugged cotton or nylon shorts.
In Rugby Union there is a lineout when the ball goes off the side of the pitch. The ball is thrown in from the sideline by a player into a line of players from each opposing team, each side lift one of their players by their shorts to gain extra height and catch the ball in the air. The player lifted up may wear special shorts for this purpose:
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