Without doubt the ability to track players with an extraordinary level of accuracy, and with immediate results, is one of the most significant advances in football over the last decade.
Time motion analysis using video replay was the cornerstone of data analytics in the late-nineties and early noughties, and during this time we learnt about players’ distance travelled, time in sprint phases, number of sprints a game, and so on.
Processing each match-day video was a time consuming process, often taking young “students” of the game many hours “coding” the data. Fast forward to 2010, and we start to hear that Manchester United are using a device that could automatically track the movement of individual players using an accelerometer. This was big news in the data analytics community, as accuracy, speed, personalisation and interaction were suddenly available at a much lower price. However, there was one big snag. FIFA didn’t ratify the use of GPS devices until 2015.
Four years on and GPS devices are commonplace in almost all professional football leagues, indicating how useful the technology truly is to coaches and players. With this in mind, we wanted to delve deeper into the technology, and chose Stéphane Smith of Titan Sensor to talk us through the technicalities of GPS.
Stéphane, first of all, what made you get into the GPS and performance tracking game?
The company’s focus is really a direct result of our staff’s collective expertise. We have physicians and surgeons on staff, former NASA engineers who developed inter-planetary robotics and satellite attitude controllers at NASA, former Intel engineers who developed technology currently running many of the world’s top ten supercomputers. By combining our collective expertise in instrumentation with the medical physiological know-how, we’ve been able to develop innovative solutions to enhance human performance and, specifically for our customers, improve gameday outcomes.
There are innumerable different kinds data to collect on athletes, everything from sleep sensors to blood work. We’ve found GPS, in particular, to be the sweet spot. It sits squarely at the intersection of low-cost, easy-to-understand, non-invasive, and highly relevant from a training, tactical analysis, and injury management perspective. GPS, when done right, is too useful (and too easy to deploy) for coaches to ignore.
Great, so in a nutshell how does GPS work?
GPS is the colloquial term for Global Navigation Satellite System (GNSS). GPS is actually the global positioning system deployed by the United States. Satellites orbiting broadcast precise time signals. The sensors receive these signals and triangulate the sensor position, velocity, and time (PVT). Various augmentations are available including Satellite-based Augmentation Systems (SBAS).
How accurate is GPS?
There are many factors affecting positional accuracy and velocity accuracy. A high-end triple GNSS sensor with full Satellite-based augmentation systems (SBAS) error correction can achieve sub-meter positional accuracy and velocity accuracy of 0.05m/s. For sports dominated by upright dynamic motion, GPS is a perfect fit in terms of measuring high accuracy data at a high update rate (10Hz).
Your new technology appears to collect much more performance metrics than other devices. Can you tell us why?
Coaches ask for them and Titan even lets coaches create their own metrics! Typically when coaches get started, they focus on key ‘plain-English’ metrics that they already have an intuitive feel for, eg. distances, speeds. Quickly though, they seek specialized metrics covering every element of play. We provide methods for coaches to select and build reports based around a subset of metrics to stay focused and communicate what matters. Coaches can also build up their own metrics like ‘Acute/Chronic Workload Ratio’.
As a footballer, which of these are the most important and why?
The most important feedback for a footballer comes from experienced coaches, who sit at the heart of game day preparation. Some sessions are designed to be hard, others easy. Some sessions may be focused on speed, other sessions on tactical situation awareness. There’s no overall most important metric, but specific metrics provide feedback for coaches. GPS sensors provide coaches with an augmented observation, and in the context of a given session, different metrics are important at different times.
Going back to your technology, we see that you have introduced video syncing and readiness surveys. These are very different metrics, is it the case that data analysts will need a more rounded understanding of physiology, performance and fatigue to interpret the data correctly?
In many cases, bringing in different ‘types’ of data (including video and readiness) removes abstraction and makes data interpretation simpler. For example, video integration lets coaches see the opponent, ball, and situational context side-by-side with metrics. With video, metrics go from being abstract numbers to being rooted in something the coach can physically see. Readiness surveying also provides a complementary angle on the data in ‘plain-English’. For example, when GPS shows a high performing athlete under performing, readiness can provide additional clues as to why and what the coach can do about it to better prepare for gameday? Poor diet? Lack of sleep? School workload? Proactively getting to the root of issues that negatively impact performance is essential, and often a simple conversation can do the trick.
Let’s look to the future. With recent advances in machine learning we envisage a time when player interactions, tactics and greater understanding of “the game” are possible. Do you believe this is the future of GPS tracking, or are you concentrating on fatigue and injury analysis?
We believe the future is helping coaches do more with less. Great teams and great players will always have great coaches in the pilot seat The technology is there to help them leverage their knowledge in ways they couldn't practically or cost-effectively do before. For example, coaching to the needs of each individual player such that they reach their maximal potential. Simultaneously enabling the team - as a collection of individuals - to reach its maximum potential as well. Machine learning, for example, can help coaches plan and even simulate the effects of training against their game day schedule to help maximize athletic and team output. The great part about GPS tracking is that it provides both tactical understanding of 'the game' as well as periodization and training optimization to manage fatigue and reduce injuries.
Finally, semi-professional football coaches may be reading this and are interested in tracking players in their clubs. What do you think they should do in the first few months of owning GPS trackers?
The most important part of using data and GPS sensors is building a team culture that values evidence based coaching. Having buy-in across the personnel stack, from players through management is more than just essential, it's the starting critical success factor. The next step is to start with the concepts and metrics they are already familiar with including speeds, distances, tactical views, video integration, readiness, periodization, acute/chronic workload ratio, etc. There are many 'right' ways of interpreting the data and I would recommend the coach collaborate with other coaches who are using GPS to compare notes.
If you are interested in buying Titan Sensor, Kit Radar are the only seller in the UK:
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