Can a horse run faster than a human over sort distance?

If the human is riding the horse, expect a tie.

Otherwise, a fast horse can run about 2 times as fast as a fast human. Humans top out at about 15 MPH (25 Km/Hr). Horses gallop at up to 30 MPH (50 Km / Hr) and quarter horses bred for short sprints have been clocked close to 50 MPH.

Both humans and horses take several seconds to get up to speed.

Most riderless horses will not gallop at full speed in the right direction when a signal is given. So if a person does a challenge, standing beside a horse when someone shouts 'go', the horse may just stand there or start walking in the 10 or 11 seconds the runner takes to reach the finish line.