Professional soccer players are often glamourised in the media – clubs spend a lot of money on them for what’s sometimes seen as 90 minutes of occasional work. But that’s far from the reality. Many European club players will play up to 60 – 70 games a year in various competitions, championships, and national teams. Games are energetically demanding and physically rough. Outside of games, players must maintain their fitness – and avoid injury.
Injuries cost clubs millions of dollars every year, and one of the greatest contributors to soccer injury is fatigue. This is not the same sort of fatigue we all feel
from lack of sleep, but fatigue of the body that results from overexertion. And there are consequences – tired muscles are less physically able to meet the demands of a game1 and even the brain and nervous system may be affected. Fatigued players may also have poorer limb control and be less motivated1.
from lack of sleep, but fatigue of the body that results from overexertion. And there are consequences – tired muscles are less physically able to meet the demands of a game1 and even the brain and nervous system may be affected. Fatigued players may also have poorer limb control and be less motivated1.
So how do coaches walk the line between training and overtraining? Clubs want fit, healthy players performing at their optimal levels – and current practices do try to incorporate rest along with a variety of training drills. But the same training protocol is unlikely to work for everyone – different field positions require different types of fitness, and individual players may require work on particular aspects of their athleticism or skill.
Getting data from individual players
Wouldn’t it be great if we could get data on the training or match performance of individual players? Well, we can. Over the last five years, Global Positioning System (GPS) technology has revolutionised the way club and national coaches assess the training loads and activity profiles of their players (for more general information on GPS technology in sports see here). Small GPS devices are attached to individual players and, by triangulating the position of the device via communication with satellites, a player’s distance and speed can be constantly monitored.
The simplest of these GPS devices can store data internally for later analysis, while more complex models can transmit the data to an on-site computer for immediate analysis. Thus, GPS allows for detailed assessment of an individual player’s physical condition throughout a competitive game and their total activity load in games and training sessions2,3. The upshot for professional clubs is they can better manage the workloads of their players and adjust their training schedules appropriately. (Wouldn’t it be great if science could sort out workload issues in other workplaces, too?)
There was initial concern that GPS tracking devices wouldn’t be accurate enough to estimate the distance and speed profiles of players – but research has now shown these fears were unfounded. It seems there’s only a 5% overestimation of actual distance travelled 3, not enough to affect the interpretation of the data.
So why don’t more clubs use GPS technology?
The obvious issue that prevents many clubs from using GPS tracking devices on their players is the expense. GPS devices that are suitable for use in sport cost more than US$1500 apiece. Imagine outfitting your entire team with these devices – a cost of more than $20,000. So, this expense prevents many professional clubs from using GPS with their players, and almost all football academies and lower-tier and non-professional clubs.
So how do we make GPS more widely accessible? Undoubtedly, players in academies and lower-division leagues still experience the issues with training loads and fatigue. Cheap and accurate GPS units would greatly enhance performance at these levels, too; and insights into an individual’s physical condition, motivation and weakness would be invaluable for those managers within a football academy wishing to develop the next crop of football talent.
Trialling affordable GPS units
Our soccerscience.net research group has recently trialled a set of small GPS units that have been developed by our own team’s GPS guru, Dr Sean FitzGibbon. Sean has vast experience in using GPS units to track koalas, and has been able to adapt that technology to suit our sports research. The small size and affordability of these units (less than US$400 each) make this within the budgets of even non-professional clubs and academies.
We placed GPS units on 15 different players within the University of Queensland Football Club during competitive matches (5 top squad females, 5 top squad males, and 5 ‘older but still got it’ players). We assessed each individual’s total distance travelled and activity profiles throughout a standard 90-minute match.
Here, we’ve provided an example of the movements of a single player during one half of a match to show you the type of data that we can collect using these devices.
In addition, we’ve provided a table representing the activity profile for one player, showing their total distance travelled throughout each half and a breakdown of their activity within six different speed ranges.
Our experience with these units suggests that we’ve come up with a solution for clubs and academies that can’t afford current GPS technology. We were easily able to record the activity profiles of our players throughout a match and represent them in an easy-to-digest format suitable for any coach. We’re really excited about this, and have a couple of studies underway using GPS on soccer players.
If you’re interested in learning more about our GPS technology or are interested in trialling this with your players, then please contact Dr Robbie Wilson ().
Coming soon
If you’re one of the UQ players that participated in our GPS trials, and want to see how your activity profiles look and compare with your teammates, then please stay tuned. We’ll be making some of these results available to you within the next few weeks.
References
1Reilly, T, Drust, B and N. Clarke. 2008. Muscle Fatigue during Football Match-play. Sports Medicine. 38: 357-367.
2 Hill-Haas, S., Dawson, B., Coutts and Rowsell, G. 2009. Physiological responses and time-motion characteristics of various small-sided soccer games in youth players. Journal of Sports Sciences DOI 10.1080/02640410802206857.
3 Edgecomb and K. Norton. 2006. Comparison of global positioning and computer based tracking systems for measuring player movement distance during Australian Football, J Sci Med Sport 9:25–32.
Written by Dr Robbie Wilson with Dr Amanda Niehaus
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