Well I could be funny and say 16, but really if you mean run the least in a match distance wise most likely 12, but much of his running is sprinting. If you mean who dose the least overall in a match that would depend on the teams game plans somewhat, but likely the 11, or blindside winger or 13. Just depends on how much ball gets out. I know in the late 80's a study showed that the pack ran like 3.2 miles and backs averaged 2.4 miles running in an average 80 minute match. Hope this helps, stay with it.
