There’s HR that increases because of exercise (stress on the body) and HR that increases due to adrenaline release (nerves). Like when your kids successfully scare the crap outta you, or you have a quick reaction avoiding a car accident. Golfers HR, if they are fit, can pump situationally, not because they are running a 100yd sprint, but because you have 5ft putt to win a $100 nassau and you only have $50 in your pocket…YIKES! or you have a 1 shot lead at the Players and slightly pull your drive, then get a fortunate bounce off a sidehill… The ability to control the nerves, like building a swing that is repetitive to muscle memory is key…controlling ones nerves, which is why, even when the heart is pumping, we can control breathing, slow down a walk, maintain your routine. The adrenaline is still there but you are controlling it and it is not contolling you, hence a good caddy giving a top end player a 54* instead of a 50* knowing the extra power lift is most likely there. I was in a study group years ago about preshot routine. The results were fascinating. People that used one obviously hit their targets more, no matter the situation, people that used the same routine, were able to execute their swings better with more center clubface hits…What was interesting to me, about me and I just never thought about it, that my particular preshot routine had little or no deviation, The entire set up for me was 14 seconds, it never deviated and if it did something would make me say internally, clock is off…start over. And, when I addressed the ball, my swing would begin everytime and take less than .83 seconds from that address when I would pull the trigger. There was less deviation than that with my wedges like .45 seconds. It becomes so ingrained, when I’m on the course I can’t pull the trigger without performing that mundane chore. Same with the putter. I’m not as consistent with the putter, because I will take a different amount of practice strokes depending on my nervousness with the putt, If I get too far out of synch, I will start it over. But great putters do the same thing everytime, they don’t deviate…A really cool example of that is in the film "The Greatest Game Ever Played, the final golfing scene, Ouimet standing over a 3ft putt for the open…and Eddie coming over and saying you got this, read it, roll it, hole it. I know there was a ton of dramatic leeway in that movie, but it does capture, adrenaline pump and how it can be controlled. If you don’t have butterflies, u’re “Better than Most”, like playing with an overnight lead., You can’t really turn it on an off like Bruce Banner and even he had to be antagonized. But you can learn to harness it when it’s there to a point, hence our routines and commitment to the shot at hand
