A laboratory-based experimental protocol for inducing psychophysiological stress in firefighters under controlled environment

Firefighting imposes concurrent physical and cognitive demands, whereas few laboratory paradigms replicate these dual-task challenges. This study developed an experimental protocol for inducing psychophysiological strain in firefighters. Twenty male firefighters (25.8 ± 3.4 years) completed a structured protocol consisting of a speech task (ST), a combined task involving load carriage with serial subtraction, and a physical task simulating hose-running. Salivary cortisol, α-amylase (sAA), dehydroepiandrosterone (DHEA), heart rate variability (HRV), and electrodermal activity were measured. Results showed marked activation of the endocrine responses, with significant increases in cortisol (122%), sAA (108%), and DHEA (138%) (all p < 0.001). Additionally, heart rate increased significantly during the ST (p = 0.007). HRV indices demonstrated pronounced autonomic modulation across stress stages. These findings support the protocol as a standardised tool for simulating occupational stress in firefighters, with potential applications in strain monitoring, protective equipment design, and wearable system development.