“…Machine learning (ML) has shown very promising results in many studies investigating data from firefighters or fNIRS tools. For instance, several studies have used ML algorithms, such as decision trees (DT), k-nearest-neighbors (KNN), and support vector machines (SVM), with physiological data such as Heart Rate Variability (HRV), body temperature, and behavior tracking sensors such as accelerometers, to detect mental workload, exertion, and stress in firefighters [ 29 , 30 , 31 ]. Similarly, other studies have used ML algorithms with other populations to detect task difficulty, mental workload, fatigue, engagement, enjoyment, and user performance [ 32 , 33 , 34 , 35 , 36 , 37 , 38 ].…”