Admit it. You’re just like me. You read about Coolmore racehorse trainer Aidan O’Brien flying horses in and out of the United States from his base in Tipperary, Ireland and you wonder, “How does he do it?”
Coolmore stars Cape Blanco and Treasure Island landed in the USA and scored victories at Arlington Park this year. The trainer has his sights set on the Breeders Cup next weekend–which he has won three times as a quick fly-in in years past–and he’ll fly his horses in not long before they race this year as well. Is he mad? Or is he just tuned in to something about racehorses that the rest of us never understood?
Until now, of course. Science has caught up with Coolmore, and just in time for the Breeders Cup, too.
A new study has shown that racehorses are extremely sensitive to changes in daily light and, unlike humans, can adapt very quickly to sudden shifts in the 24-hour light-dark cycle, such as those resulting from a transmeridian flight. Not only can racehorses adapt–they may actually enhance their physical performance by spending time zipping around the planet on a plane.
Are you having trouble imagining that you could fly to Europe or Africa or the Middle East and arrive ready to run–let alone race? Well, you’re obviously not a Thoroughbred. A long flight? A change of time zones? Wondering what day it is? Ho hum, let’s go for a run…
And then you find out that your performance is even better than it was at home.
The research by scientists at the University of Bristol’s Faculty of Medical and Veterinary Sciences in England is published in the Journal of Neuroendocrinology.
“Our study shows that racehorses are different from humans in that they rely on light cues for their daily rhythms of activity.”
This is the first study of its kind to investigate the effects of jet lag on the physiology and performance of racehorses under tightly controlled experimental conditions. Apparently horses are the only athletes, apart from humans, regularly flown across time zones for athletic competitions.
Dr Domingo Tortonese, Senior Lecturer in Anatomy in the School of Veterinary Sciences, who led the study, said: “We tested the hypothesis that abrupt alterations in the 24-hour light-dark cycle, such as those associated with the crossing of time-zones, would alter the molecular clockwork and neuroendocrine systems of racehorses with detrimental consequences on their athletic performance.
“In humans, air travel-associated sudden changes in the 24-hour light-dark cycle disrupt biological rhythms with negative effects on cognitive and physical performance. Indeed, jetlag has important implications for athletes who travel across time zones for competitive sporting events, particularly after an easterly flight.
“Our study shows that racehorses are different from humans in that they rely on light cues for their daily rhythms of activity, rather than for the synchronisation of an endogenously generated rhythm to the 24-hour light—dark cycle. This light dependency underlies a rapid process of adaptation with critical scientific implications and unexpected practical benefits.”
This brief video, provided by the Hong Kong Jockey Club, shows sport horses arriving in Hong Kong in the summer of 2008 in preparation for the Olympic Games equestrian events. The research from the University of Bristol begs the obvious question: does the time zone and travel oblivion of racing-fit Thoroughbreds extend to their warmblood cousins and other breeds, like Quarter horses shipped for reining competitions?
Thoroughbred horses with previous race training were housed in light-controlled rooms and put through a fitness program of daily sessions of exercise on a high-speed treadmill at variable times of the day for three months. They then experienced a shift in the 24-hour light-dark cycle that mimicked an easterly flight across seven time zones.
The 24-hour patterns of four clock genes, together with neuroendocrine systems involved in a variety of functions, including time measurement, homeostasis and the response to stress, were investigated before and after the shift. The aerobic and anaerobic capacities were measured by standardized performance tests. Locomotor activity was also assessed continuously, under photoperiodic conditions and in the absence of light cues (constant darkness), to determine the expression and robustness of a 24-hour rest-activity cycle. The speed of re-adaptation to a new light-dark cycle was also investigated.
Contrary to the prediction based on human and rodent data, the results show that even though horses are extremely sensitive to sudden changes in the 24-hour light-dark cycle, they can adapt very quickly to a phase shift. Importantly, this rapid adaptation is not accompanied by an increase in the level of stress, but by alterations in endocrine systems that favor an enhancement of the horse’s physical capacity during the process.
The improvement in athletic performance following experimental jet lag resulted in the animals being able to run at full gallop for an additional 25 seconds before reaching fatigue. This differs from humans who show a slow adjustment, particularly after an eastbound flight, with detrimental consequences on performance. The difference between the two species can be attributed to the powerful masking effect of light on the horse’s daily locomotor activity, which, together with the absence of a robust sleep-wake cycle, can be a part of a mechanism of adaptation to sudden changes in the environment.
The results of this study have important practical implications, since equine athletes do not need to travel to be subjected to changes in daily light, and its beneficial consequences could help to reduce the level of injury in competitions.
The research by the University of Bristol, in collaboration with colleagues from the University of Melbourne and the University of Cambridge, was supported by a research grant from Great Britain’s Horserace Betting Levy Board and by a Wellcome Trust Equipment Grant.
What day is it anyway? Don’t ask Aidan O’Brien’s horses when they land in Kentucky next week for the Breeders Cup. They could care less. They’re just coming to run.
Reference: Experimental jetlag disrupts circadian clock genes but improves performance in racehorses after light-dependent rapid resetting of neuroendocrine systems and the rest-activity cycle, Tortonese D J, Preedy D F, Hesketh S A, Webb H N, Wilkinson E S, Allen W R, Fuller C J, Townsend J, Short R V. Journal of Neuroendocrinology, published online ahead of print, 15 September 2011.
by Fran Jurga
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