Super effort
by Dan Retief 09/03/2010, 09:42
Modern rugby has been likened to the human body being subjected to a series of car crashes and now there is scientific evidence to back it up.
I was staggered recently by the amazing information contained in an article penned by Ross Tucker, an expert in sports physiology, in a Press release from sports drink company Powerade.
Tucker, who holds a PhD in exercise physiology from the UCT Faculty of Health Sciences, has been commissioned by the Minister of Sport to draw up South Africa’s high performance plan for Olympic sports and consults to the SA Sevens team.
Having long been fascinated by the supreme effort required of the players in Super 14 rugby Tucker’s opening line caught my eye: “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…”
Anyone who has ever travelled a long way east from South Africa will tell you about the debilitating, disorientating effect of jet lag but imagine what it must be like while constantly being mugged by thugs from the penal colony or rough Kiwi manual labourers?
Well, this is how tough it actually is. According to Ross Tucker 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.
*The GPS devices are attached to a vest worn under the players’ jerseys. The chip is placed between the shoulder blades, where it is unlikely to be damaged and can pick up a player’s heart rate - the signal being sent to a computer at the side of the field which stores the data.
These studies, conducted in England and Wales, 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 7 and 7.5 km a match, while forwards cover between 5 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 5 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 3 to 4 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 (finally there’s proof!), 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 1700 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!
The equipment being used to monitor players was first developed in Australia’s AFL and Tucker says he is looking forward to studies being done comparing the southern hemisphere to the northern hemisphere and perhaps providing conclusive proof to the contention that “the Super 14 is the hardest rugby competition in the world.”
Still not convinced or impressed? Try this. Go out on the lawn. Stand upright. Chest out. Now lie down. Now stand up. Now lie down again. Now stand up. Now lie down again, perhaps get the dog to jump on you… okay keep going - you only have 79 minutes and 50 seconds to go!