This week, the European Hockey Championships will be held in Antwerp. Hockey is a sport in which the Netherlands traditionally does well. However, competition has grown over the years and that means that The Netherlands has to become smarter both on and off the field. Research institutes are being called upon to help optimize the individual qualities of the players.

After all, although hockey is a team sport, each player has his or her own personal playbook. This concerns both the apparent talents and more hidden factors such as recovery time and mental stress outside of training sessions. These variables require individualized training says biomedical R&D engineer Heleen Boers from Imec Nederland. But how do you get a clear picture of these variables? Along with other projects, Imec is working on a 24-hour monitoring system with Nano4Sports, supported by funds from Interreg Europe. They accomplish this by using a watch that continually displays each individual’s reaction to mental stress.

Heleen Boers (© imec)

Nano4Sports aims tot bring innovative technology to both recreational and professional sports, Boers explains. “The great thing about it is that every case is based on a practical question. This is also one of the pillars of the project, we do not develop something just because, as researchers, we think it’s great, it’s about the athletes who think it is needed. There was a demand for 24/7 monitoring across hockey and football.”

Nowadays, measuring heart rate, speed and distances covered during training is normal. This allows a coach to assess the impact of a training session on an individual. “Outside the training, little else is measured. For example, one person can have a very high heart rate during training and someone else can have a lower heart rate. Afterwards, the high heart rate may drop quickly and the lower heart rate might remain relatively high. In the latter case, the body does not go into recovery mode. You want the muscles to recover and the body to be ready for the next workout.” Currently, applications from brands like Fitbit, Garmin and Suunto measure heart rate, sleep and sometimes temperature throughout the day. This provides a lot of information, although it says nothing about cause and effect.

Skin conductivity says a lot about stress levels

Excessive exertion can be the cause behind a slower recovery. “You keep going and your heart rate doesn’t slow down. That’s why you don’t respond well to training anymore, you’re kind of leveling out.” Yet there are also external factors that influence your recovery, according to Boers. “Like stress. Which has nothing to do with your training but does affect your rest. Do you have a lot to do outside of your training? Do you have time to switch to recovery mode? – That part of your mental state.” The research institute explored whether the newly developed watch measures physical parameters associated with the amount of stress experienced using hundreds of their own employees. The watch measures the conductivity of your skin, the level of perspiration. ” The conductivity of your skin is very sensitive to changes in your level of alertness, your stress system. For example, if you are shocked by a car racing by, the conductivity of your skin will increase and you will sweat more.

Watch (© imec)

The research revealed that the level of stress experienced by a person and how the body reacts to it is very personal. “What we want to examine now is how this mental component plays a role. If athletes say they are experiencing stress, the watch measures how the body reacts to that.” Last summer, ten rowers monitored their recovery time and their perceived stress. They wore the watch day and night, except during training, as they have their own heart rate monitors then. They also filled out a standard questionnaire and an app would ask them several times a day how much stress they were experiencing. “If you are able to monitor this fully, you are able to recognize patterns. For example, if someone experiences stress each time before a competition. Both athlete and coach are then able to personalize the training schedule.”

Daphne van der Velden welcomes this personalized approach. Van der Velden is a physiotherapist and hockey player in the Oranje-Rood team, winners of the 2019 Dutch premier league. “It bolsters a trainer when they can decide that it is better for an athlete to train a little less intensively. Especially with young athletes who, for whatever reason, suffer from mental stress, such as exam stress or stress in their private lives. Young people are still growing and such mental pressure affects the capacity of the player or athlete. Further training at the same level can lead to overexertion. This is not sufficiently taken into account at the moment.”

She herself experienced a reaction to mental stress during the last season. “I was working  thirty hours a week, had to study twenty hours for my Master’s in Sports Physiotherapy, train seven times and compete in a match. I got all kinds of issues, it was all too much. Something had to change. Get the peace and quiet to be able to study. That’ s when I started working six hours less. The issues disappeared.”

Better insight into how the body reacts to stress is also important for the athlete themselves, says Van der Velden. “In this sense, I’ m a bit more educated now and I am aware that everything has to be in balance. I imagine that some other athletes can’t make that link, but with a watch like that they probably could.”

Imec Nederland will be presenting the results of its research during the sports and innovation congress on October the 7th.