Jockeys lose 2-5% body mass on race days via dehydration, raising injury risk

Professional jockeys must weigh 112-126 lbs to ride, forcing chronic weight management that frequently crosses into dangerous territory. On race days, jockeys typically lose 2-5% of body mass — and in extreme cases up to 7% — primarily through deliberate dehydration using saunas, hot baths, and diuretics. This level of dehydration measurably raises heart rate, reduces muscular strength, impairs reaction time, and degrades thermoregulation. For an athlete controlling a 1,200-lb animal at 40 mph in a pack of 10+ horses, impaired reaction time is not an abstract concern — it directly increases the probability of falls, interference incidents, and pile-ups that injure both horses and riders. CDC/NIOSH has flagged jockey occupational hazards, yet minimum weight limits have barely changed in decades. The problem persists structurally because lower jockey weight is believed to give horses a competitive edge, creating a race-to-the-bottom where any individual jockey who maintains a healthy weight loses mounts to lighter competitors. No collective mechanism exists to raise minimums industry-wide because each state racing commission sets its own weight scales.