Coaches use drills to reinforce the movement concepts they teach, so it’s important to understand why a drill is used. Coach Parno breaks down the concepts behind the hurdle wall drills, wickets, and toe drags and explains why and how he uses them in is track and field program.
The wearable sensor market is growing, and has now stabilized enough to review the leading companies and systems available. Tracking and managing the external load of training is here for good, and the space is only going to get busier and more demanding. Instead of just including a list of what is popular or available to coaches, we’ve decided to explain the evolution of the equipment and software so coaches can see where things are going before investing a lot of money in them. We’ve also included some sport science history, so teams can better use other data sets that might make more sense than buying inappropriate devices.
Some Definitions of Player Tracking and Player Loading Concepts
Even someone in the sports technology field will use incorrect terms like “GPS” or similar because the wearable market has a stigma, so it’s important to get on the same page with proper terminology. Player tracking or monitoring is growing beyond just a few cutting-edge teams, and it’s now at the high school level. In a few years, the wearable device for athletes will be ubiquitous, just like the smartphone is currently the new normal for the general population. Athlete data is now a part of the job requirement of new hires, and if you are not familiar with technology, some jobs will simply not be available to you no matter how great your coaching is.
The difference between tracking and loading is like the old square and rectangle analogy—a square is a type of rectangle, but a rectangle is not a square. Tracking a player is simply observing simple indices and locations of what the player is doing, and loading is trying to estimate the general summary of demand on the player’s body. While the concepts are similar, loading is trying to measure the demand on the body for managing adaptation and injury risk, while tracking is more superficial observation of what work was done.
Vague but still useful data like total distance covered is a metric worth noting, but any sport scientist or coach worth their salt will explain that without specific context and an array of other data sources, it’s just a number in isolation. When teams invest in wearable devices they are looking for information that requires more than a pair of eyes and a watch—something more precise and automated. When you invest in wearables, you are paying for the convenience and accuracy of what was done in training or competition, not revealing something that is shocking or novel. If you find or reveal a lot of new patterns or trends from player tracking devices, you will likely struggle when the next evolutionary step comes in a few years.
An easy explanation to remember is that loading is more about the mechanical strain on the body, and tracking is more about the descriptive details of the total amount of work. When loading, think about how much force the body is taking, and with tracking think about what the body is producing.
How Wearables Work and Why They Sometimes Fail
The term “wearable” is a very wide category in sport, as something simple like a modern textile T-shirt is in that category. Most coaches equate GPS devices for rugby and soccer as wearables, and while that is correct, the industry is going to explode beyond just a torso sensor. In fact, the reason the market has not evolved much is not because of technology, but the gap between sport science practice and the team coach. Some systems were cost-prohibitive in the past, but now new systems are inexpensive enough that high school teams are adopting them. With cost barriers gone, the important next step is to see how sports wearable devices work in helping teams manage workload beyond the simple variables.
Key Sensors in the Technology
Four primary sensors are likely inside a wearable device, and the system is usually placed on the upper back area of the torso. Each individual sensor provides direct information, such as the GPS module and the accelerometer, or supports the sensors that collect the data, like the gyros or the magnetometer. Indoor systems don’t use GPS, obviously, and other options exist for positional information besides GPS. Still, the everyday wearable will likely have sensors similar to the ones listed below.
Accelerometer: This sensor is the most common one we see because it is reliable and cheap. Accelerometers measure changes in rates of perceived force, but not actual forces like strain gauges and similar. The accelerometer can detect acceleration change inside the device, but the calculations are generally in a vacuum.
Gyro: Gyros help provide orientation for wearable devices using Earth’s gravity, and are used to give direction to the accelerometer data. Without gyros, the accelerometers would give a lot of raw work data, but could not provide sophisticated details that give deeper insight. Gyros are more important in barbell tracking and projectiles, but are still vital for body sensors.
Magnetometer: Like a gyro, a magnetometer supports accelerometers to enhance the resonance of the data by helping the orientation of the direction of the data. Using the magnetic field of Earth, this sensor is useful for a general reference point of the data and is not as essential as the accelerometer and gyros.
GPS Module: You could swap in other satellite-positioning networks, but GPS modules are so inexpensive and useful for gathering distance measures that companies will continue to use them. As they get closer to the 1-meter standard, GPS sensors will become better for true work rates and velocities. Most satellite-positioning systems are too inaccurate to use for timing speed, but they are good enough for ballpark estimates of tracking, like distribution of estimated velocities. The sampling rate of GPS modules is the reason they are not ideal for getting exact speeds and speed curves of players. Local networks can be created for indoor arenas or as a more precise alternative to GPS.
The sensors are not the true cost of the product; the real expense is in the calculations or algorithms needed to make sense of the sensor data. Algorithms range from amazing demonstrations of mathematics to bad formulas just used to get an estimate in a rushed project. Any time you hear “algorithm,” remember to think “smart guessing.” No algorithm is perfect because it is just a calculation based on available data and appropriate math. The good news is that most of the products available can lead to better perspectives that help move the decision-making forward, as they are good-quality data feeds. What is really limiting coaches is the lack of a modeling of data collected with other information sets to make the best decision.
One strong word of caution: Most wearable sensors are poor estimations of the center of mass and the lower back is better for locomotive data, but they are good enough to estimate work done. As stated in another review, foot sensors will likely disrupt the torso tracking option, as they are better measures of loading and provide real gait data, as opposed to the general and crude data of accelerometry. Also, we are going to see IMUs get to the point they are close to camera-based motion capture by the end of this decade. With countless other sensors that can get biometric data from the skin and other organ systems, the data well is going to overflow, so get into good habits now with easier data like tracking information.
The Science and Research Validation of Player Tracking
We have been very critical of athlete tracking for years, not because of the accuracy or precision of the data, but because of the practitioners who use it to look busy or progressive. Years ago—a decade in fact—only elite clubs could afford the cost of specialized sensors, so it was difficult to know who was doing something intelligent with the data collected. As in the Force Plate review article, what you are trying to measure determines how useful the tracking data is. In sports like rugby and soccer, the style of play and size of the field makes it sensible to want to know the workload of players, but in sports like professional basketball, baseball, and the NFL, it’s limited.
Player-tracking technology data is good in general measures, but not appropriate beyond raw summary totals. Martin Buchheit wrote a thought-provoking piece on monitoring with GPS by auditing a few companies, but for the most part what is valid is total distance and the distribution of peak velocities reached based on time. What is disturbing is data can’t be compared year to year, as upgrades to hardware and algorithms simply make it impossible to interchange the data from season to season or athlete to athlete. With different companies on the market—even if they are owned by a parent company—standardization is not currently available. Some research has been done on how hard hits or tackles are, and the detection of high-effort activities has also been studied. The real question is, “What information do you expect to capture that you can’t see with your own eyes?”
The prime example of sport science futility is an NFL team that invested in a GPS system to move into the data-driven age of modern sport, but crashed badly after a few weeks. American football uses measurements on the field and the plays are mostly scripted, so practices shouldn’t be that difficult to measure. Since football practice is mainly a closed and choreographed routine rehearsal, distance is easy and players are near 90-100%. If position and team coaches are organized, most systems don’t add a lot of value. What player-tracking technology does offer is more granularity and easy management of the data through automation and more detail.Player-tracking technology is external load measurement, not the biological response. Click To Tweet
A safe summary of the precision and accuracy of systems is that they are good enough to detect an event, but expecting more than just a tally system on the work performed is stretching what the technology can currently do. The technology should be used to take the step beyond minutes, ratings of perceived exertion, and heart rate zones. Athlete-tracking data is really adding a cleaner view of practice work, and is a part of monitoring but not monitoring itself. Player-tracking technology is external load measurement, not the biological response. Good management of practice loads is a never-ending check and balance of the type of work placed on the athlete and how they adapt or fatigue to that stimuli.
What to Look for in Software and Hardware
Hardware, or the specifications of the sensors, has already been generally reviewed. What is essential is the sampling rate of the GPS modules, as the rest of the details are less variable. The faster the sampling frequency of the GPS or positional sensors, the more likely a true velocity is captured.
Currently, the sampling rates are fast enough to determine a running athlete’s peak speed, but not enough to measure changes in speed development in training. For the most part, the faster the hertz, the better the data. Battery life, transfer speed, and connectivity of physiological data like heart rate are all noise as the differences are so trivial it doesn’t change the game, but the more useful features the better. Overall, the difference between an entry-point product and top-of-the-line system is small or non-existent. A higher price tag does not necessarily mean more power, but the more-expensive product will usually perform a better calculation of work and other small benefits like impact loads.
Software is a mixed bag, because it’s usually developed last in the development process. Teams want the player tracking data to migrate to their athlete management system; they don’t want to be stuck with an internal software system unless it offers really good analysis features. With plenty of big brains at the pro level, the sport scientists and crafty coaches want the data exported for real data mining, not just more charts on the dashboard.
On the other hand, there are small clubs and scholastic teams that need a way to have more of a bottom-up approach to this process, because a team coach may just have an assistant managing the training and data and that’s it. They are lucky to have anyone in sports medicine on the scene for emergencies, and sport science is just wishful thinking outside basic hydration and the need to strength-train intelligently. Having a slick app or great team software is vital for the small club, so companies still need to do more than just provide a table view of the data. With heat maps, high-intensity event summaries, and velocity bands, coaches have enough information to make a good decision on what to do with practices.
The Current Options in Player Tracking and Load Management
Nearly everyone is familiar with the brands and companies listed, so we will get into the small nuances that make them unique or promising. Some companies have been around for years and some just started on the market. We expect a rapid rise in new market players, and a bubble a few years later. For now, here are some products worth considering.
Catapult: The leading company in player tracking is Catapult Sports, an Australian company that is the wearable data juggernaut. They have some serious investments and a vast client list, but they also have an issue sustaining growth, due to the cost of their product and the limited number of elite teams in sport. They have struggled to expand to more sports, since most of the current interest is from outdoor field sports. Other environments like baseball and ice hockey make player tracking difficult and limited overall. Their product is best suited for top professional teams or top college football programs. While they do support basketball, professional levels are more about competition and travel, as practices resemble half court walkthrough sessions or shoot-arounds between games.
GPSports: This is another Australian company and they’re in a state of transition. While they battled Catapult in the space for years, Catapult bought GPSports in July 2014 and now they’re looking for their own identity. We’re not sure if the current market can support a product that doesn’t differentiate, so it will be difficult for us to predict the future of the company other than just checking with teams still using them.
KINEXON: KINEXON’s core product is an ultrawide band (UWB) based tracking technology, which is suitable for both indoor and outdoor environments. It provides inch-accurate position/motion data in real-time and is able to seamlessly connect to other wearables. KINEXON also developed a state of the art and easy to use web application providing essential indicators for training control, injury prevention and tactics. KINEXON is based out of Munich, Germany and opened a US subsidiary in New York City in 2016. It quickly became one of the leading providers of player tracking for indoor sports, with clients in the NBA, NHL and NCAA.
STATSports: This Irish company is now making noise again after launching their new APEX product. One of the strengths of the product is connectivity between other wearables, a move that will be emulated by others down the road. STATSports has a leading product, and they just released their update this summer. Along with live monitoring, the system works on a tablet and they have an OLED display on their pods.
Polar USA: Strangely, Polar Sport decided recently, like Adidas, to get into the player tracking space with their team system. Known for heart rate monitoring, they are currently providing an alternative to Catapult and they are gaining some momentum with early adopters. We have not seen too many U.S. clubs buying into them, but because of their history with physiological monitoring they have a leg up with streaming both data sets to coaches. Heart rate data is still important to measure, especially with soccer and rugby, so Polar made a strategic choice to consolidate the process with their team GPS system.
GPEXE: This new company from Italy is using a 20Hz system—a reflection of the price drop in GPS modules and rate of evolution of hardware. Several other features, including rapid data transfer, and their promotion of metabolic power equations are enticing. We like that this company is small and nimble, and they are going to need to continue being so to stay in business as the new wave of cost-friendly products are going to reshape the industry. A million athletes at the youth level can afford an entry point product, so new companies are going to be major threats to the current powerhouses.
PLAYERTEK: The most inexpensive option on the market is one that is almost too good to be true with data quality. Catapult acquired PLAYERTEK in 2016 because they were a threat long-term, with virtually the same product at a fraction of the price. The software is gorgeous and easy to use, and the hardware is well-designed. To us, PLAYERTEK represents the right mix of function and cost.
We didn’t include VX Sport and Precision Sports Technologies because of market saturation and the fact we have not seen them live. Expect more companies to join the list of options for teams as the youth sport craze fuels the need for data. Also keep in mind that several watch companies provide a simple way to get gross workloads, like Suunto and Garmin. They are more interested in the endurance market, as that is larger and easier to support due to the linear structure of aerobic sports.
What the Future Holds for Player Tracking and Load Systems
The future is going to be a Wild West, and that is a good thing for innovation but a headache for validation. Any startup company can claim they provide state-of-the-art technology, but without independent testing, be cautious but open-minded.
Expect the next frontier to be a rekindling of a promising concept presented 10 years ago called Body Area Networks or BANs. The future is digging deeper into how the entire body works as one unit, so BANs will connect all types of sensors of the body for a richer view of what is going on in real time. How coaches take advantage of this information will be the real end game, as collecting data is only the first step—making that data useful is the last.