"Swimming coaches are often poolside with a stopwatch in hand," says Ganzevles. They use the stopwatch to track each swimmer's time for each length, while also observing the number of strokes per length and the rhythm of these strokes. “With more swimmers, it becomes increasingly difficult for coaches to keep accurate track of everyone’s statistics.”
This led Ganzevles to develop a device as part of his doctoral research that could be used by coaches and swimmers to efficiently and meaningfully gather and review the desired data. “The device needed to be practical for both the coach and the swimmer and, of course, reliably accurate in its measurements.”
Career
Ganzevles himself competed at a high level, including in European and World Championships. After ending his swimming career in 2004, he began his journey as a sports scientist, studying movement science at VU Amsterdam. In 2010, Ganzevles started working as an embedded scientist for the Royal Dutch Swimming Federation, with the goal of putting scientific principles into practice. Over time, he began coaching for the Dutch national team. Following the Olympics, he worked as a head coach at the Federal Training Centre in Heidelberg, Germany, before moving to Australia. He now leads the high-performance program for Swimming New South Wales at the University of Newcastle.
Waterproof and Real-Time
Through his work as a scientist and coach, Ganzevles realised that existing wearables failed to meet the needs of swimmers and coaches. “Most wearables only measure one specific variable, whereas coaches are interested in a combination of multiple variables,” Ganzevles explains. “Additionally, accuracy is often lacking, and the data cannot be transmitted in real-time during swimming. Perhaps most importantly, many devices aren’t waterproof.”
To support coaches, Ganzevles first developed a model that offers a practical strategy for tracking swimmers’ performance. "Based on that model, we created a device capable of measuring each stroke and lap during swim training. These measurements are taken with greater accuracy than a coach can achieve with a stopwatch." The device transmits real-time information to the poolside, including lap times, stroke count (both per lap and per minute), and heart rate.
Fluidity
Beyond traditional data like lap times and stroke count, Ganzevles introduced a new variable: “jerk,” which provides information about the fluidity of the swimming movements. “More jerk indicates a jerkier swimming motion,” Ganzevles explains, “which requires more energy to maintain the same speed.”
With this information, coaches and swimmers can better monitor and further optimise performance. Ganzevles explains, “They can see if the training is going according to plan, identify areas where the swimmer deviates, and adjust the training as necessary. This allows performance to be even better managed, with the hope of winning more medals!”
The device was tested by top swimmers at national training centres in Amsterdam and Eindhoven during their daily training sessions. Data was also collected from swimmers in Australia.
This device isn’t just for professional swimmers, Ganzevles emphasises. “Swimmers of all levels can benefit from using this wearable and approach, from competitive swimmers to triathletes. It can also be used to measure any activity in the water – for example, other water sports or for people who need water-based rehabilitation.”