In this paper we associate features obtained from
ECG signals with the expected levels of stress of real
firefighters in action when facing specific events such as fires or
car accidents. Five firefighters were monitored using wearable
technology collecting ECG signals. Heart rate and heart rate
variability features were analyzed in consecutive 5-min
intervals during several types of events. A questionnaire was
used to rank these types of events according to stress and
fatigue and a measure of association was applied to compare
this ranking to the ECG features. Results indicate associations
between this ranking and both heart rate and heart rate
variability features extracted in the time domain. Finally, an
example of differences in inter personal responses to stressful
events is shown and discussed, motivating future challenges
within this research field.