The power delivered by a horse is highly variable depending on several factors (like the breed, state of health etc.) so this was later standardised and a value of 745.699 Watt is taken as 1hp. So technically you cannot consider 1hp as the power of one horse as the statement is highly ambiguous. read more
Having a lot of horsepower at your disposal doesn't mean you have to use it, if you drive a high horsepower corvette around at 65mph on the highway, it'll also last forever, but no one actually does that. read more
Originally, it was estimated that one horsepower was the work done by a single horse. It's all based on on that observational estimation. Of course, every horse has a different capability. read more