Technology & Innovation
Sensors in sport
Healthier
exercising with
sensors
Text Jos Wassink
Injury-free exercising: is it possible? Research funder NWO has devoted a five-year research program to this question. It concluded at the end of March. TU Delft and Vrije Universiteit Amsterdam are leading this so-called CAS program.
The sensor trousers contain five sensors recording accelerations and rotations.
©Sam Rentmeester
In addition to being inconvenient for athletes, sports injuries are also often the reason why people quit sports, according to Prof. Frans van der Helm (Faculty of Mechanical, Maritime and Materials Engineering (3mE). What’s more, injuries can be costly: think treatment and absenteeism costs because people with an injury cannot go to work. Van der Helm, program leader of the NWO’s Citius Altius Sanius (faster, higher, healthier) perspective program, cites a figure of 5 billion euros per annum.
‘The sensor trousers are entirely flexible and washable, including the wiring’
Conversely, there is a research budget totalling 6.2 million euros, within which twelve doctoral candidates and two researchers, among others, have worked over the past five years. Led by TU Delft and Vrije Universiteit Amsterdam, the CAS program’s main goal is to develop technology that prevents injuries. Four other universities, two institutes of higher education, twenty-eight companies and eleven sports associations joined in the efforts. The researchers are working on sensor technology, data science and feedback technology, applied in cooling and in running, football and field hockey, baseball and tennis, fitness and strength training and cycling, among others.
RunningBuddy app
The RunningBuddy app is a digital running coach. The earplugs by Dopple, a Dutch company, contain accelerometers from which step frequency and step height can be derived. RunningBuddy distinguishes between four running styles: bounce (low tempo, high jumps, like a springbok), push (high tempo, minor height difference, like an ostrich), stick (low tempo, minor height difference, like a polar bear) and hop (high tempo, major height difference, like a rabbit). The app needs about three minutes to analyse a person’s running style and then offers prompts to adjust the running style. So, does it prevent injuries? Not necessarily, the researchers say. The app introduces runners to a slightly different running style that may be faster or less strenuous.
To prevent injury, more information would be needed about a person’s fitness, running history and goals. The RunningBuddy does not currently allow for that.
Sensor trousers
Football and field hockey are notorious for the risk of knee injuries. To get a better handle on this issue, the group of Prof. Kaspar Jansen (Faculty of Industrial Design Engineering) has developed sensor trousers. The long model contains five sensors: on the back, both upper legs and both lower legs. The shorts come with three sensors. Each sensor records accelerations and rotations in three directions and transmits them to a box on the back the size of a mobile phone. Apart from the box, the trousers are entirely flexible and washable, including the wiring. For now, the box stores movement data on an SD card, but there are plans to transmit the data to, for example, the coach or medical staff on the sidelines. So, what can they do with the data? They can monitor peak intensity for each player or see fatigue building up, says doctoral candidate Bram Bastiaansen (Human Movement Sciences at the University of Groningen).
One might even imagine a small meter that indicates the remaining stamina or activity per player between green and red. As such, the sensor trousers could complement the sports tracking system Inmotio that tracks the position of all players during a game.
Further research
“But the key question is: has this program prevented even a single injury?” says Van der Helm. Leaving the question unanswered, he says the development from a prototype into a product on the market takes at least as long as the development of the prototype. In that sense, the program that has now been concluded gets them halfway there. Prof. Peter Beek, professor of Human Movement Sciences at VU Amsterdam, agrees. He would be keen on an open research program CAS 2.0, where the emphasis shifts from sensors to performance enhancement and injury prevention.