I would ask you why you think track running isn't measured by the runner's feet then as well. Why does a runner cross a finish line when they cross with their head and shoulders?
If you look closely The defenders offside line is drawn from his knee a playable part of his body
I would ask you why you think track running isn't measured by the runner's feet then as well. Why does a runner cross a finish line when they cross with their head and shoulders?