The first rule of fighting is:
1) Don’t Get Hit
The second rule of fighting is:
2) You Will Get Hit
Here’s a fact of life: real fights start cold, your character will have zero time to warm up their body or prepare their muscles. They won’t have a chance to get their body into perfect condition before the first attack comes, so the chances of them pulling or straining a muscle is high, even if they win the fight. They will be bruised, they will be battered, and their injuries will stay with them for weeks, if not months.
One of the hardest truths of combat is that no injury ever really heals. Even with medical attention, the injury will stay with the character. For an example: Go watch some of Jackie Chan’s earliest movies and then one like “The Karate/Kung Fu Kid”. You’ll notice that even though he is still an amazing fighter, he cannot really walk straight anymore. And Jackie Chan doesn’t even actually fight, he just practices martial arts and occasionally jumps off the Brooklyn Bridge.
Fighting puts constant stress on the body and wears it out quickly, even if your character is taking fewer hits and isn’t stupid, they’re still going to hurt in the aftermath. Whether or not your character takes pride in their bumps and bruises is up to them, but the body will wear out. If you as a writer ignore that, then your characterization and story will suffer.