An Australian researcher reported he's found a reliable way for trainers to monitor Thoroughbred racehorse fitness using global positioning system (GPS) technology measurements of velocity and heart rate during normal fast gallop training routines. David Evans, BVSc, PhD, associate professor in the Faculty of Veterinary Science at the University of Sydney, presented his research at the 51st Annual Convention of the American Association of Equine Practitioners, held Dec. 3-7, 2005, in Seattle, Wash.

"The three fundamental measurements during exercise that are used in the assessment of fitness are maximum oxygen uptake (VO2max; which training aims to increase), blood lactate, and heart rates," Evans said. "Measuring VO2max is the gold standard for aerobic fitness, but this involves putting a mask on the horse's face and exercising at high speeds on a suitable horse treadmill, so this technique has been limited to research in laboratories." He said measuring blood lactate concentrations during and after exercise is an excellent approach, and decreases in blood lactate during submaximal exercise reflect improved aerobic fitness. However, this method has also been mostly limited to the treadmill lab because the procedure is invasive, and exercise protocols are difficult to standardize in field fitness tests, especially in Thoroughbreds.

Evans was searching for an assessment method that was non-invasive, readily acceptable by jockeys and trainers, rugged, reliable, and able to produce repeatable numbers. He applied GPS, a validated technology that can measure velocity and position at frequent time intervals, in a study of 10 Thoroughbreds that had already completed six weeks of slow training and one week of fast-gallop work under the same trainer.

The horses wore heart rate monitors and their jockeys wore GPS receivers in their skull caps during their fast gallop workouts, with batteries and GPS data loggers on board. Measurements were taken before, during, and after four weeks of commercial training for racing. The equipment gathered five-second averages of heart rate and velocity.

Evans found significant increases (8%) in the velocity at which the horses reached their maximum heart rate (VHRmax). He also found significant increases in the velocity corresponding to a heart rate of 200 beats/minute in these horses (8.3%). "It doesn't show us the mechanism (by which fitness levels are increasing), except that the heart rate probably became lower during submaximal exercise, because cardiac stroke volume (the amount of blood pumped out of the ventricles of the heart with a single contraction) increases with training," he added.

Additionally, these young horses could also have learned to gallop more efficiently.

Trainers could also use the fitness assessment data to refine training programs. A trainer can use the HR-velocity measurement to tell the jockey to gallop horses at specific gallop speeds to promote stamina fitness, and he can tailor future training sessions to the horse's physical status.

This fitness testing method "tells us that VHRmax is relevant to Thoroughbred performance, it's accurate and precise (within 2%), you can measure without directly observing the horse at all times during its gallop, and it can be used to record sectional times and peak velocities," Evans concluded. He said it was easily included in a busy stable routine and was readily accepted by trainers and jockeys. A prior Japanese study showed that superior Thoroughbred racehorses had a higher VHRmax.

The equipment could one day be used to examine the relationship between VHRmax and racing performance over different distances and in males and females, and could assess horses with poor performance or loss of performance and their responses to treatment.

Australian trainers are using a GPS fitness assessment system prototype in which the data is downloaded after the horses' gallops and the numbers are calculated automatically.

"The company, Nature Vet Australia, has told me they would like to launch the product in early 2006," Evans said.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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