Relaxation versus tension

I know my most powerful punch is a completely relaxed technique but tension is needed on impact to protect the hand/wrist if you make a bad connection.

Yet, when the shit hits the fan I know I'll be pretty tense and being tense means a less smooth, less powerful strike.

Even boxing doesn't desensitize me and boxing is a million times less stressful than two guys who are considering whether to stamp on you.

How do you maintain relaxation under extreme stress for maximum power?

Is this one reason you favour the slap since there is less tension in the arm with an open hand?

My main 'trick' to help that problem was always to have a different STARTING hand position to the finishing one.. so start with OPEN hand to finish with a punch and a fist shape to finish with an open hand

Open hand before a punch - yep, been working that for a while (courtesy of Neil and Keith's relentless commitment to getting me to relax!!), and it really does work.

Never thought about the other way round though - starting with a fist (presume pretty loose) when throwing a open hand strike.
Simple but mind blowing - have t o try that one.

Thanks for the idea - anything different helps to make home training exciting rather than a chore...

Cheers
Paul