Your Body Has Two Settings for Stress, and Your Blood Vessels Know the Difference
In the healthy version, blood vessels open wide to send blood where it is needed, and the body bounces back to normal faster.
Science Vs · Stress: The Science of Chilling OutWhen stress hits, your heart beats faster and your breathing quickens. Part of what decides whether that surge helps or hurts is what your blood vessels do next.
In the harmful mode, which researchers call the threat response, the heart pumps harder but the vessels stay narrow. Blood cannot move easily to the arms, legs, and brain. The system is out of sync, with the pump working and the pipes closed, and that mismatch is part of why this kind of stress is thought to wear on the body.
In the helpful mode, called the challenge response, the vessels widen. More blood flows outward to the muscles and brain, and the body releases building hormones that support performance. Jeremy Jamieson, a University of Rochester psychologist, first noticed the difference as a college football player, watching teammates get amped up before a game in a way that was seen as supportive for performance.
The same person can experience either response. The difference seems to depend on whether you feel ready to handle the stress. Researchers think the challenge response also shifts the hormone mix, producing less cortisol, the classic stress hormone, and relatively more testosterone, which acts here as a short-term performance enhancer.
That shift matters after the moment passes. Testosterone is cleared from the body quickly, so after a challenge response the body returns to its resting balance fast.
Questions people ask
Can you nudge yourself from threat into challenge?
That is the idea Jamieson tested. He taught people that a racing heart and sweaty hands are fuel for the task ahead, to encourage them to see the stressor as something they could handle. These segments do not report whether that lesson changed blood vessel responses.
Is the testosterone part only relevant for men?
No. Women make testosterone too, in the ovaries and adrenal glands, just in smaller amounts than men. In this context it is not about aggression or sex drive, but about a short-lived signal that supports energy and performance and then clears quickly.
Does a challenge response mean no cortisol at all?
No. Researchers think you still make some cortisol in a challenge response, just less of it relative to testosterone. Cortisol is part of any stress arousal, mobilizing energy. The difference is the ratio and how fast the body returns to baseline.