For major surgeries Midazolam is generally used primarily as the main anisthetic. Its a very fast active benzodiazapine with very short half life, it hits you like a nuclear warhead and PUTS YOU DOWN AND OUT but 5 minutes after waking up from it there are literally no more noticeable side effects.
Of course they warm up before the fight. But anyone who has had nagging injuries will tell you they can be sporadic. You can warm up before an exercise or sport all you want, sometimes you just don't feel comfortable into the second or third set, or when the adrenaline is really kicking in. Maybe it wasn't. Maybe it was. But I'm not sure how anyone can be so sure of something.
Like Pacquiao's 2015 shoulder surgery... from his jet-ski accident in 2009! His words, not mine... Probably don't get the operation if the fight goes their way.
That's not how shoulder injuries work. A shoulder injury warranting surgery does not warm up, it only gets worse