Pre-exercise cooling may help Thoroughbreds in hot training
Bottom line
Cooling horses before exercise may help Thoroughbreds handle short, intense work in hot conditions without sacrificing performance. In a new randomized crossover study from the Japan Racing Association’s Equine Research Institute, six trained Thoroughbreds completed three different pre-exercise routines in a hot environment with a wet-bulb globe temperature of about 32.5°C: 30 minutes of walking, 30 minutes of standing rest, or a 10-minute shower at about 26.2°C before warmup. The shower group lost less body weight and showed lower pulmonary artery temperatures than the walking group, while run time, heart rate, plasma lactate, and rectal temperature did not differ significantly across treatments. The authors concluded that pre-exercise cooling mitigated weight loss and body temperature elevation without affecting performance. (jstage.jst.go.jp)
Why it matters: For veterinary professionals working with equine athletes in hot climates, the findings add support to a practical heat-mitigation step before training or competition, especially where sweat loss, dehydration, and exertional heat illness are concerns. Broader literature and industry guidance already frame heat stress as a major welfare issue in horses, and emphasize that early detection plus effective cooling strategies are central to reducing risk in hot, humid environments. (link.springer.com)
What to watch: Expect more discussion around how pre-cooling protocols could be incorporated into training barns, racetrack management, and event heat-preparedness plans, particularly as hot-weather welfare guidance continues to evolve. (fei.org)
Key facts
- Study design
- Randomized crossover study
- Study population
- Six trained Thoroughbreds
- Setting
- Hot environment, wet-bulb globe temperature about 32.5°C
- Pre-exercise routines
- 30 minutes walking, 30 minutes standing rest, or a 10-minute shower at about 26.2°C
- Main finding
- The shower group lost less body weight and had lower pulmonary artery temperatures than the walking group
- Performance outcome
- Run time, heart rate, plasma lactate, and rectal temperature did not differ significantly
- Conclusion
- Pre-exercise cooling reduced weight loss and body temperature elevation without affecting performance
- Limitation
- Small study under controlled conditions
A new study suggests that cooling Thoroughbreds before warmup in hot conditions could help preserve hydration status and limit heat buildup without hurting performance. Researchers at the Japan Racing Association’s Equine Research Institute tested six trained Thoroughbreds in a randomized crossover design and found that a 10-minute shower before exercise reduced body weight loss and lowered pulmonary artery temperature compared with a 30-minute walking pre-treatment, while run time to exhaustion did not change. (jstage.jst.go.jp)
The work arrives as heat stress remains a growing welfare and performance issue across equine sport. A recent literature review described heat stress as a serious concern not only in racing and elite competition, but also in leisure riding, transport, and general management under hot, humid conditions. That review also emphasized that prompt recognition of heat stress and effective cooling methods, including cool water and airflow, are important for horse welfare. (link.springer.com)
In the new paper, horses underwent three pre-exercise conditions in a hot room with a wet-bulb globe temperature of 32.5 ± 0.5°C: 30 minutes of treadmill walking at 1.7 m/sec, 30 minutes of standing rest, or a 10-minute shower at 26.2 ± 0.8°C. After that, all horses completed a brief warmup and then a high-intensity treadmill bout at roughly 115% of VO2max until exhaustion. The shower treatment significantly reduced post-exercise body weight loss versus both walking and rest, and pulmonary artery temperature was lower than in the walking group after pre-treatment, warmup, and main exercise. Heart rate, plasma lactate, rectal temperature, and run time did not differ significantly, suggesting the cooling intervention improved thermal and fluid-related measures without blunting performance. (jstage.jst.go.jp)
That distinction matters because warmup is usually meant to prepare horses physiologically for work, but in hot environments it can also add thermal strain before the main effort begins. The authors specifically noted that walking in a hot environment before exercise is not recommended for preventing exertional heat illness because it raises body temperature, and they suggested that a short, moderate-intensity warmup after pre-cooling may be sufficient. (jstage.jst.go.jp)
While direct outside commentary on this specific paper was limited, the findings fit with broader expert guidance from equestrian bodies and prior research. FEI heat-preparedness materials emphasize acclimatization, access to water and ice, cooling stations, shade, ventilation, and familiarity with cold-water cooling protocols at events. EquiManagement’s own recent reporting has also highlighted that horses training or competing in hot climates may benefit from targeted heat-mitigation strategies, including acclimatization and cooling interventions. (inside.fei.org)
Why it matters: For equine veterinarians, trainers, and support teams, this study offers a practical pre-exercise management option that may reduce sweat-related weight loss and internal heat load in hot climates without compromising short-duration performance. That could be especially relevant for racetrack settings, high-intensity training sessions, and events where horses face repeated exposure to thermal stress. It also reinforces a broader clinical point: heat-risk management shouldn’t begin only after exercise ends. Pre-exercise planning, acclimatization, hydration oversight, and cooling logistics may all shape outcomes before a horse ever enters the main workload. (jstage.jst.go.jp)
There are still limits to keep in mind. This was a small study involving six trained Thoroughbreds under controlled conditions, so field performance in different breeds, disciplines, climates, and competition formats still needs study. Even so, the signal is clinically useful: if pre-cooling can lower thermal strain without reducing output, it may become a more common part of hot-weather protocols. (jstage.jst.go.jp)
What to watch: The next step will be whether larger field studies, racing authorities, and sport governing bodies translate pre-cooling evidence into formal hot-weather recommendations for training and competition management. (inside.fei.org)