Mixed

Strenuous occupational activities, specifically fire suppression, training, and alarm response, significantly increase the relative risk of on-duty coronary heart disease (CHD) death in firefighters compared to non-emergency duties.

For high-stress occupations involving sudden bursts of extreme exertion (like firefighting, military combat, or heavy labor), the risk of cardiac events is not just about long-term health but about the acute trigger of strenuous activity. If you have underlying cardiovascular risk factors (age, smoking, hypertension), high-intensity bursts can precipitate failure. Regular medical screening and fitness maintenance are critical to handle these acute demands safely.