The article explains the significant impact of run-up distances—the untimed stretch before the official race distance begins—on horse racing pace fractions and final times. In North America, run-up distances vary widely, affecting how fast or slow early fractions appear. A longer run-up allows horses to accelerate before timing starts, producing faster-looking fractions, while a shorter or no run-up includes acceleration in the timed portion, resulting in slower fractions. This discrepancy can mislead bettors analyzing race performances, especially since run-up distances are not always clearly reported.

Using data from Churchill Downs, where the 6-furlong dirt sprint run-up was progressively shortened from 200 feet to about 30 feet, the article shows that shorter run-ups consistently produced slower fractional and final times—by nearly a full second on average. For example, sub-:22 opening quarters dropped from 77% of races with a 200-foot run-up to just 5% with 50 feet or less. Understanding these effects helps bettors better evaluate true horse speed and standout performances, such as Bentornato’s impressive times despite a shorter run-up, highlighting the importance of considering run-up distances in handicapping.