How does adrenaline affect your heart rate during stress?
During a fight-or-flight response, adrenaline can triple your heart rate within seconds.
When you sense danger, your adrenal glands release adrenaline to prepare your body for immediate action. This hormone triggers your heart to pump oxygen-rich blood to your muscles at high speed, delivering the sudden strength and energy needed to survive an emergency. Your heart rate can surge from a resting 60 to 100 beats per minute to over 200 beats per minute in just a few heartbeats.
Nerd Mode
The fight-or-flight response was first described by Harvard physiologist Walter Cannon in 1915. When your brain's amygdala perceives a threat, it sends a distress signal to the hypothalamus, which activates the sympathetic nervous system. This triggers the adrenal medulla to release epinephrine—also known as adrenaline—into the bloodstream.Adrenaline acts on beta-adrenergic receptors in heart muscle cells, increasing the firing rate of the sinoatrial node (your heart's natural pacemaker) and enhancing the force of each contraction. A resting heart rate of 60 to 100 beats per minute can surge to over 200 beats per minute within seconds.This physiological reaction is part of the Acute Stress Response. Beyond the heart, adrenaline causes bronchodilation in the lungs to increase oxygen intake and stimulates the liver to release glucose for immediate energy. Research published in the Journal of Clinical Investigation shows that these systemic changes occur almost instantaneously, ensuring your body is primed for survival during life-threatening events.
Verified Fact
FP-0003684 · Feb 18, 2026