Question on heart-rate before and after a crash

A reader writes, Dear AR1, I recall the ABC Indy 500 team commenting that James Jakes heart rate actually went down during the moments he was working to avoid contact with one of the race's crashes. I haven't heard or read any further reporting on the dropping heart rate, and I find it counter-intuitive to conventional fight or flight reflexes. Has AR1 heard anything further on the matter? Keep up the great reporting of IndyCar. Bob Pagels, Downers Grove, IL

Dear Bob, You are exactly correct in that in normal people with anxiety or stress, the adrenalin can cause the heart rate to escalate; however, if he took a deep breath and held it to escape this moment or even paused his breathing during this reaction time interval, his heart rate could have actually gone down.

The valsalva (holding your breath) maneuver actually causes a block to the node that serves as the pacemaker for the heart and can actually slow the rate for a few seconds or more….that, may help us explain what happened. If we had continued to watch after this near miss moment, his heart rate would have spiked upward to compensate. Thanks for the question, very insightful of you to ask. Dr. Jerry Punch