Thoroughbreds Are Running as Fast as They Can | FiveThirtyEight: The data reflected remarkable achievements by the fastest horses, dogs and people. Denny fit the data with a statistical model, and then used extreme value theory (since the data was about the best in each sport) to calculate a maximum speed limit.1 Some race times, like the Kentucky Derby’s, have plateaued, while others are still improving, like the men’s 100-meter race. This approach suggests that the fastest time possible for a human in a 100-meter race is 9.48 seconds. Usain Bolt’s world-record time is only 0.10 seconds from the limit.2
Denny says his approach tells us “that speed has its limits, but not what accounts for those limits.” There are, however, a few possible explanations for why thoroughbreds may have already hit those limits but humans, for the most part, have not yet plateaued.