Captain America (Marvel) is in peak human condition due to the effects of the Super Soldier Serum.
Possess and remain in peak physical and/or mental condition with little or no maintaining
"Look—humans can throw a 100 miles-per-hour fastball, smash concrete blocks with their heads, and run 4.2 forties. What they can't do is all of that at once. It's not so much physical as... as mentally impossible. Too much to coordinate."
―Batgirl #14 (May 2001)
The power to remain in the peak physical and/or mental condition of user's species with little or no maintaining.
The user is at the peak physical and/or mental condition of their particular species in that verse can achieve without any super-/unnatural methods. This usually entails that they are faster, stronger, more intelligent and overall superior to fellow members of their species without being obviously supernatural.