Presumably, this means about 5km are covered at walking or jogging at less than half speed. Your average referee spends 5.47 minutes of the game running at that high intensity speed.
A lot of the rest of the 74 and a half minutes is spent walking or jogging - if you watch closely you will notice the modern referee spends a lot of time walking from phase to phase, tackle to ruck or maul, sometimes breaking into a jog if play is moving across the field more quickly.
For more than half the game (43.43 minutes in fact) the average referee's heart rate is above 80 per cent of its maximum.
So apart from all that running, jogging and walking, there may be a few other things that cause a referee's heart rate to increase considerably.
Think dealing with a number of players who may be trying to exert undue pressure on the referee through constant complaining or worse.
Or having to deal with foul play like sinbinnings or sending-offs - it is not easy to remain cool, calm and collected at these pressure times.
On the subject of running at high intensity speed, a referee can expect to sprint 13 times during a game, sprinting from 6-40 metres at a time.
Intercept tries can easily lengthen these figures, but fortunately they occur infrequently.
All these figures interested me because while refereeing a senior (now premier) game at Spriggens Park in the late seventies I borrowed JB Phillips' new toy - a pedometer - to use to try to find out how far I ran during a game.
My guess was about 7km but the reading at the end of the game surprised me - 4.5km.
Maybe the game was a bit slower in those days, or more likely, I had set the distance of each step too low - the pedometer was a crude device that simply measured the number of steps you took.
I averaged out my running step of just over a metre and my walking step of about half that distance and punched in the average for each step.
Set your average too high and you got a ridiculously low distance reading, and the opposite also applied.
The interesting thing is though that, based on the figures published and used in this article, my guess of about 7km was probably surprisingly accurate.
Now, all I have to do is work out how far I have run over 50 years of refereeing, averaging maybe 15 to 20 matches per season, and I might be on the way to understanding why at least one of my joints is showing signs of wear and tear.
I caught the last 10 minutes of Thursday night's Otago-Auckland Mitre 10 Cup match.
Apart from being very pleased with the outcome, I noted that the Lindsay Colling Memorial Trophy had been regained by the southerners.
Colling was an Otago, Auckland and All Blacks halfback who moved to Auckland for a job in a sporting firm about the same time I arrived to teach in Cromwell.
I got to meet him on a number of occasions as his parents bought the "middle" pub in Cromwell while I was there.
He was one of the four Colling and three Clark brothers who won the national seven-a-side tournament that was played in Ashburton in 1971.
He was also a good mate of infamous prop Keith Murdoch.
I spent an hour in their company at the pub shortly after Murdoch arrived back from the 1970 South African tour.
He had played the last three or four tour games, including two test matches, with a rumbling appendix and had to stay behind for an operation while the rest of the All Blacks travelled back to New Zealand.
Murdoch was either very inarticulate or extremely shy, because in that hour all he ever muttered was, "yes", "no," or a simple grunt to all questions.
As an aside, it is said that he got off his 1972 international flight in Australia before it arrived back in New Zealand, after he was sent home for dealing to an officious security guard after the Welsh test in which he scored the winning try.
I know that he did return to New Zealand after the 1972-73 tour of Great Britain, as I saw him at the Cromwell New Year's Day races a few months later.
Keith was a big man and surprisingly quick when he ran with the ball, but I wonder how far he, and modern-day props, ran during their games?
Whatever, he remains the hairiest man I ever saw, as close to a bear as I have ever seen.