I wear a heart rate monitor when I stream videogames, and wrote a simple visualization sparkline/beating heart I could throw in as an overlay. I was surprised at the variability of my HR in various situations, from lows of around 60 to highs in the 140s.

Even in 'normal' parts of the gameplay when I wasn't under stress I'd see my heart rate shifting all over the place. One moment of calm I'd be at 65, then 80, then 70. I started playing with it, to see if I could swing the needle with breathing, and quickly found that gamifying it led to my heart rate increasing when I was successful at decreasing it. (I'd get excited that I had lowered the rate, which increased the rate.)

I was also surprised to learn that my heart rate spiked significantly after tense moments in the game. In game combat usually didn't cause the rate to rise until 30 seconds or so after the combat started. I felt the intensity and the rush immediately, but the HR increased later.

I also found that games slowly lose their HR impact over time. A game like Player Unknown's Battlegrounds could get my HR into the 120s pretty easily, and now it only raises my HR into the 90s when it's tense.

It's fun to have access to all this data about ourselves, and I'm glad to see so many different ways of using it -- from dialing in a few extra % on your athletic goals to showing goofy SVGs over a videogame.