If it's what I think it is, it measures the strain that moderate exercise (like walking a treadmill) puts on your heart. The way they get the readings, though, is by sticking little sensor stickers all over your chest area... I had them on my ribs and sides the last time they had to check mine. It wasn't a stress test, but yeah. Little stickers all over. I'm guessing that's what he's referring to, because I may have bit back a reaction or two myself under similar circumstances.