That is according to injury expert Ben Dinnery, who runs the Premier Injuries site and has a background in medicine and data analysis.
Celtic ran out 2-0 winners at Motherwell on 16 October thanks to goals from Filipe Jota and David Turnbull.
But the Scottish Premiership clash was paused for five minutes at the half-hour mark as referee Collum required treatment on an ankle injury.
He was replaced at half-time by fourth official Chris Fordyce who saw out the remainder of the game.
Dinnery remarked on referees’ exceptional fitness standards and claimed Collum’s departure was the exception which proves the rule.
“Most people don’t realise these guys are really fit,” he told Football Insider correspondent Adam Williams.
“They need to have a really good base level of fitness and be able to keep up with the pros. You rarely ever see them go off.
“At the highest level, referees will cover 11, 12, 13km per game. That’s roughly the same as players do. It’s amazing.
“When one does go off injured like in this Celtic match, it’s always a novelty, which is quite remarkable, really.
“They have sports science department and undergo pre-season tests to make sure they are maintaining their levels.
“You also need to be able to mimic the game on the training pitches too, so it’s a big job.
“They are at the top of the profession and really look after themselves.”
Celtic followed up their 2-0 victory at Fir Park with another 2-0 win over Ferencvaros in the Europa League yesterday (19 October).
This article was originally posted here