My Heart Rate doubles...at least. Maybe I am still trading with emotions?
A few years ago an analysis was done of aircrash/aircraft fire survivors.
Dealing with emergencies does not come easily to many people it seems.
It transpired that those who survived had the skill of planning how to deal with emergency and the calmness and clearheadedness to carry out their plan dispassionately when everyone around them was panicking.
Perhaps the same survivor types are able to trade successfully for the same reasons.
Regarding pulse rate, it is quite possible to control it. The commonest approach seems to be yoga and/or breathing exercises. 20 years ago when I was a club runner I could make my resting pulse go up or down at will between 53 and 39, although not through yoga, more through 'knowing' my own body from years of using it - a kind of bio-feedback.
Also consider the effects of caffeine and nicotine, tiredness, frustration, hunger/thirst, calls of nature, distractions, etc. and the thoughts that one's strategy may not be the golden goose it appeared to be, and the periodic inability to accept losses as part of the statistical odds, and move on. All of these and more will affect pulse rate once you have entered a trade.
Arguably pulse rate is the barometer of how much you are in control of what you are doing.
Glenn