LIGHT
LET THERE BE LIGHT
How daylight affects racehorse performance and safety Recipient of multiple awards, including the Saratoga Trainer’s Title and the Eclipse Award for Outstanding Trainer, Bill Mott is no stranger to traveling with his horses. For example, Mott was trainer and chaperone of Cigar, winner of the inaugural Dubai World Cup in 1996. How do Mott and other elite trainers consider the impact of jet lag, lightdark cycles, and other factors associated with shipping across times zones on their horses’ performance? WORDS: STACEY OKE DVM, MSc PHOTOS: Marc Reuhl, SHUTTERSTOCK
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N general, traveling by plane to places like Dubai isn’t that much different than taking a van between New York and Florida. They both take about 22 hours, but I find that flying internationally turns a horse’s biological clock upside down and does seem to throw them off for a day or two…but they do seem to turnaround quicker than we do,” shares Mott.
Rhythm is a racehorse
In reference to biological clocks, Mott is of course referring to circadian rhythms—near 24-hour cycles of behavioral, physical, and biochemical processes that ebb and flow like ocean tides. The sun that rises and sets every day is the center of our universe and drives the internal clocks of all organisms, including horses. “The light-dark cycle in a 24-hour period is one of the most important environmental cues—referred to as zeitgebers—that coordinate an animal’s internal clock to the earth’s 24-hour rotation,” explains Barbara Murphy, BScEq, PhD, from the School of Agriculture and Food Science, University College Dublin, Ireland; Murphy is an expert in the field of circadian rhythms in horses. According to Murphy, physical activity, body temperature, heart rate, blood pressure, hormone levels, sleepiness, among other body functions, undergo rhythmic undulations over the 24-hour period in response to a number of external cues including light, temperature, feedings, and social interactions.
She adds, “Synchronization between an animal’s daily rhythms and their environment helps ensure optimum survival by allowing them to anticipate activity, feed availability, and predation pressure.” Thus, even slight alterations in an organism’s daily cycle or “rhythm” can negatively impact a large variety of body systems, including athletic performance.
International travel, jet lag, and racehorse performance
As Mott has learned through experience, horses do experience jet lag; but Mott inherently concludes that a horse’s jet lag doesn’t seem to affect horses as profoundly as it affects us. Mott’s personal experience is actually quite astute, and one published study—dubbed the “jet lag study”— confirms Motts assertions. According to the jet lag study (published in a 2011 edition of the Journal of Neuroendocrinology), crossing several time zones in a short period of time results in a mismatch between an individual’s biological clock and the “new” solar time. As many of us know, classic signs of mismatch (i.e., jet lag) in humans include disturbances in sleep and gastrointestinal, cognitive, and psychomotor function, including athleticism. For example, it is reportedly disadvantageous for human athletes (e.g., baseball players) to travel eastward prior to competitions. Considering how common it now is for horses to travel internationally for athletic competitions, the research team from Bristol University, led by Domingo Tortonese,
DVM, DrVetSci, PhD, simulated jet lag in former racing Thoroughbreds using light-controlled stables and a high-speed treadmill. The study found that horses, unlike humans, are capable of rapidly adapting to changes in their photoperiod and that their body responds to jet lag in such a way that enhances their physical performance. Specifically, the horses were able to run at a full gallop on a treadmill for an additional 25 seconds before reaching the point of fatigue. The study authors concluded that horses are exquisitely sensitive to sudden alterations in light-dark cycles. They also suggested that a horse’s ability to adapt to changes in light-dark cycles could be because horses lack a “robust” sleepwake cycle, meaning that horses sleep more in a “fits and bursts” type of pattern and require only a fraction of the sleep needed by humans to behave like civilized creatures. Another interesting feature of the jet lag study was that, “…the rapid adaptation of horses to photoperiodic changes is not accompanied by an increase in the level of stress but by alterations in neuroendocrine systems that favor an enhancement of their physical capacity during the process.” Those findings, however, contradict results from an earlier study on jet lag in horses published in the Journal of Circadian Rhythm in 2006 by Murphy, et al. “We found that body temperature rhythms were out of synch with the environment for two weeks following a six-hour time zone transition,” explains Murphy. ISSUE 35 TRAINERMAGAZINE.COM
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