The relationship of subsequent racing performance to foreleg flight patterns during racing speed workouts of unraced 2-year-old Thoroughbred racehorses at auctions

Abstract

Workouts of 980 unraced 2-year-old Thoroughbred racehorses at major U.S. auctions were videotaped using digital high-speed video equipment (ie, slow motion) and studied for signs of extraneous foreleg motion.a Extraneous foreleg motion included, but was not limited to: 1) hyper rotation of the cannon bone on an axis parallel to the plane of the running surface (ie, moving in sagittal plane; hoof hitting an elbow in extreme cases) and perpendicular to the direction of the racetrack longitudinally; and 2) foreleg flight patterns not symmetrical and/or not parallel to the vector of the forward momentum of the horse's center of gravity (eg, winging, paddling, and/or wobbling at joints). Experienced Thorough bred racehorse industry videographers and gait analysis researchers were trained and used as film reviewers who rated foreleg motion on a scale of 1 to 5, with 1 indicating little or no extraneous motion, 3.5 indicating average extraneous motion (relative to the other unraced 2-year-olds at these auctions and to more than 20,000 similar horses at similar auctions over the past 10 years), and 5 indicating extreme extraneous motion (ie, at least 1 standard deviation or more from the mean). Because these were subjective ratings, only the more extreme rankings were used for comparison purposes in this study—that is, a minority (15.3%) of the overall study population. A group of 73 horses with “good” foreleg motion had ratings from 1 to 3. A group of 77 horses with “bad” foreleg motion had ratings from 4 to 5. The subsequent North American racing performance of horses with good and bad foreleg motion was compared. Both groups had similar average velocity and similar distribution patterns of the velocities of the workouts, so the differences between the groups that are discussed in this study were not caused by different overall workout velocities. Extraneous foreleg motion was shown to be related to subsequent racing earnings and the level of racing competition achieved. Horses with good foreleg motion (as defined herein) earned more and had greater stakes-level success than horses with bad foreleg motion. For example, the median earnings per start of horses with good foreleg motion was 83% higher than those of horses with bad foreleg motion, and horses with good foreleg motion were 58% more likely to win a top race (ie, one designated as a “graded” stakes) than horses with bad foreleg motion. However, the “good movers” raced less overall than the “bad movers.” A secondary finding of this study is that although there is a widely held industry belief that horses with high action or bad foreleg motion are more suited to turf racing, horses with good foreleg motion were more likely than horses with bad foreleg motion to race at least once on turf, and, among horses to race on turf, horses with good foreleg motion were more likely than horses with bad foreleg motion to win and to finish “in the money” (ie, at least third).