The Vodacom Super 14 competition puts elite rugby players through one of the toughest tests in the game – with up to 15 maximum efforts over 16 weeks, often across 10 time-zones against teams wishing to displace the Bulls as the reigning Super Rugby champions.


Ross Tucker
But exactly what is the physiological challenge faced by players in any given match?

Recent developments in technology have allowed the physiological demands of the game to be accurately quantified using GPS devices, giving us information on distance covered, running speed, heart rate, intensity of player impacts (g-force), and energy expended during matches.

These studies have shown the following:

– A backline player will experience about 120 ‘impacts’ per match – an impact is any involvement in a tackle, ruck/maul, or collision with the ground. Not surprisingly, forwards are involved in more impacts than backline players, with about 300 per match. Of these, 70 have a g-force greater than 8g, and the majority of impacts, somewhat surprisingly, come in the second half (65% compared to 35%).

– In terms of running, backline players can expect to cover between 7km and 7.5km a match, while forwards cover between 5km and 7km, depending on their playing position (loose forwards covering the most distance). About 70% of the match is spent standing or walking, 25% is spent jogging, and 5% running at sprinting speeds. This means that for every second spent running, players will rest or move slowly for about five seconds.

– However, the real challenge lies in the number of times players have to change speeds, either accelerating or decelerating for short periods. The average ‘sprint’ is 20 metres long, and it happens 30 times a match, while fast jogging for 20m happens 90 times a match. In total, there are shifts in speed approximately 750 times per player per match, or once every three to four seconds. The challenge in terms of conditioning is to prepare players for this constant shifting of pace and direction.

– Forwards spend more time doing very high intensity exercise, and less time walking or standing than backline players (65% of the match for forwards, compared to 75% for backs). This is explained by the forwards having more ‘static exertion’ periods – scrums, rucking and mauling. The result is that overall, even though backs do more running during a match; they actually do less total work than forwards. For example, in an 80-minute match, a loose forward can expect to burn about 2000 kCal, compared to 1 700 kCal for backline players. This is 25% higher than what has been measured for professional soccer players. By way of comparison, a 90kg man running a half-marathon (21km) burns about the same amount of energy as a Super 14 player every weekend!

– Finally, the physiological load is actually greater in the second half of matches. Players run further in the second half, with more accelerations and short sprints, and there are twice as many impacts in the second half. More time is also spent doing high-intensity running and less time walking in the second half of matches, especially for forwards, which says that play is more continuous in the second half. It’s perhaps not surprising then that scorelines often remain tight for 50 minutes before opening up – the last 30 minutes is where the physiology begins to tell!

Ross Tucker has PhD in Exercise Physiology from the UCT Faculty of Health Sciences and is currently a member of Paul Treu’s SA Sevens management team.

8 Responses to Physiological demands of rugby

  • 1

    Now this is what I call interesting…. come on Prof Tim Noakes, if or when you read this, kindly add some more substance for us!

  • 2

    Sal like om Skala se stats te sien van so 2jaar terug teenoor nou….

  • 3

    2@ Koning – My jinne, jy LEWEEEEEEEEEEEEE!!

    Hoe gaan dit, flok!

  • 4

    Gaan maar bedonnerd! Flippen warm hier innie Kaap en die kinders hou ‘n man besig. Ek kan nie meer wag vir naweke nie, nie oor die rugby nie, maar oor die extra slaap!!

  • 5

    4@ Koning – Hahahaha, klink of jy ‘n naweek weg kort…. weg van alles en almal.

  • 6

    Exercise, aging and humour
    Who says you lose speed with age? 72-year old granny runs down a teenage hand-bag thief

    No, this is not Part 3 of the series I started last week on Exercise and Aging. But, it was too good an opportunity to pass up, because it fits so well, and makes the perfect “weekend interlude”.

    You can read the story here. It describes how 72-year Jean Hirst of Derbyshire, England, ran down a 15-year bag thief when she tried to make off with Mrs Hirst’s handbag.

    In the article it describes how the thief had a head start, but Mrs Hirst says she covered 70 yards in about 15 seconds and the girl, with a look of “sheer amazement” on her face, was forced to throw the bag aside when Mrs Hirst was within two strides of her in order to escape!

    A big thumbs up for Mrs Hirst for turning back the clock – she was a junior sprint champion at 17.

    And I’m guessing that the 15-year old “failed” bag thief is not a prospective London 2012 runner. Thumbs down for stealing from an apparently helpless pensioner, and also for letting that head start slip!

    A repeat performance – England has some sprint talent (in the over-65 category)

    Amazingly enough, it turns out that this is NOT THE FIRST such occurrence in England – either England has the fastest pensioners in the world, or the slowest teenagers, because in doing a bit of research after receving the story from Jim Ferstle (thanks as always, Jim!), I found this story from October 2008:

    Granny Janet Lane runs teenager to ground over snatched pension

    Same situation, except Mrs Lane was 68, and the theives were boys. Incredibly, Mrs Lane ran them down despite wearing sandals. She had been a cross-country champion back in 1953, and had apparently kept herself in shape ever since!

    So another thumbs up for Janet Lane! And another thumbs down for those British teenagers – lacking morals, as well as fast twitch muscle fibers!

    Last word is a quote by Jean Hirst:

    I didn’t think of my safety, but I did pay for it a little the next day. I was covered in aches and pains and my daughter turned to me and said it was because I didn’t warm up properly.

    Have a great weekend, and join me for the rest of the series on Aging next week!

    Ross

  • 7

    Superbul, I didn’t know if I should laugh or cry…..

    ‘Super Gran’ The Movie….

  • 8

    Jeezzz! No wonder guys have on and off seasons.
    I spend 400 cals in the pool and I feel it the rest of the day.
    When I do weight training I can feel the difference between doing a mile swim the day before and resting the day before. And that is only 400 cals!

    Spending 2000 cals in 90 minutes is crazy! To put it context: 2000 cals are the recommended TOTAL food intake for an average person per day (FDA).

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