Drinking a structured water product on markers of hydration, airway health and heart rate variability in Thoroughbred racehorses: a small-scale, clinical field trial

Racehorses in training are in situations of repeated stress that may have effects on hydration and health, including airway health. The main hypothesis of this descriptive study was that daily consumption of a structured water (SW) product for 4 weeks will result in improved hydration, reduced markers of upper airway health concerns and increased heart rate variability. Two groups of Thoroughbred racehorses matched for physiological, training and racing attributes were studied for 4 weeks. One group (n = 17) received 10 L (~15%) of their daily water as SW (followed by ad libitum filtered deep well water) and the control group (n = 15) only filtered deep well water. Duplicate (two separate days) blood samples and bioelectrical impedance analysis (BIA) measures were obtained at baseline, 2 and 4 weeks. Hydration was assessed using BIA. The upper airway was assessed by nasopharyngeal endoscopy at baseline within 60 minutes of breezing (weekly near-race gallop pace). On weekly breeze days heart rate was recorded at rest, during exercise and recovery and data were analysed for heart rate variability. Compared to controls, horses drinking SW showed: (a) increased hydration by 2 weeks that was sustained to 4 weeks; (b) upper airway health (less mucous and less trace bleeding) post-breezing; and (c) increased heart rate variability (more restorative autonomic response) at rest. There were no performance benefits, no adverse events occurred, and blood hematological and biochemistry parameters were normal throughout. It is concluded that drinking 10 L daily of SW increased hydration and may have conferred some wellness benefits.