Cardiovascular diseases are the primary cause of death worldwide. Chronic stress and obesity are important risk factors for the development of all cardiovascular diseases. Studies have shown that firefighters seem to be at higher risk of cardiovascular death, and one possible explanation is high levels of chronic stress in addition to a routine in favour of fat weight gain. An autonomic imbalance in favour of sympathetic activation to the detriment of vagal modulation might be an underlying mechanism for increased cardiovascular risk. This could trigger an acute event in a susceptible population, for instance, firefighters who undergo major stress.

Mendes et al. (2023) tested firefighters’ autonomic response during acute mental stress (3 minutes of Stroop colour word test) and its relationship to adipose tissue. The authors sought to investigate possible physiological parameters which would impact the heart rate response to mental stress. In their study, mental stress decreased vagal modulation (RMSSD) and increased heart rate and blood pressure. Therefore, the group of participants was separated into three subgroups according to heart rate response. Even with different heart rate and RMSSD responses, blood pressure increased similarly between the subgroups. However, the subgroup with lower body fat responded with higher heart rate during mental stress. This result was confirmed using multiple linear regression.

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