A soft sensor based on FBG technology for heart rate monitoring in archery

Archery is a static sport that requires high postural stability during shooting since every tiniest movement can negatively compromise the archer's performance. One of the main crucial activities responsible for involuntary movements is the heart beating. However, keeping low HR is not always implementable especially during biggest tournaments. Innovative technology such as wearables can serve as an important opportunity to quantitatively measure HR during practice and competition without limiting the archer movements. In the literature, wearable inertial units (IMUs) have been proposed for monitoring HR but their rigidness and low body compliance limit the use in the field. Soft sensors can overcome this issue by improving the adherence to the skin through the sensor encapsulation into flexible substrates. Soft sensors based on Fiber Bragg gratings (FBGs) are reaching growing interest for HR monitoring due to their superior properties (e.g., miniaturized size, high sensitivity to strain, good frequency response and capability of working in harsh environments) over conventional methods. This study exploits the advantages of an FBG-based soft for HR monitoring in archery. Firstly, the fabrication and the metrological characterization of the soft sensor was described. Then, a preliminary assessment was carried out to investigate the sensor performance in HR monitoring. The promising results together with the possibility of automatically identifying the shooting session on the FBG signal will be useful for driving personalized training strategies according to the way in which the athlete responses to stressful conditions during both practice and official tournaments.