Comparison of Cardiovascular Fitness Measures Determined Under Saddle or on a High-Speed Treadmill

Standardized exercise tests (SETs) are often used to measure cardiovascular fitness in horses. Cardiovascular fitness is commonly expressed as the velocity at which a horse obtains a heart rate of 160 beats/min (bpm; V160), 180 bpm (V180), and 200 bpm (V200). Adding an incline to the treadmill during exercise mimics the added intensity of carried weight under saddle. Although previous work evaluated workload between the 2 exercise methods, little work has compared the cardiovascular fitness measures obtained from the treadmill and racetrack. Thus, the study objective was to compare cardiovascular fitness parameters V160, V180, and V200 in horses undergoing SETs under saddle on a racetrack and on a high-speed treadmill. Eight mature Thoroughbred racehorses underwent SETs on a 1,200-m dirt-sand racetrack under saddle. Horses wore on-board heart rate monitors with GPS to track distance, velocity, and duration of exercise. The racetrack SET was then replicated on a high-speed treadmill at 3° incline. Body weight was collected before exercise. Weight of the rider and tack was also collected before the racetrack SET. Linear regression equations were used to calculate V160, V180, and V200 for each horse using heart rate and velocity for each SET. The subsequent fitness measures were each compared using Student’s paired t-test. Mean biases of cardiovascular fitness measures between the treadmill and racetrack were compared using ANOVA. A Pearson correlation was used to determine the relationship between mean bias and the weight of the rider and tack as a percentage of body weight. Results (mean ± SEM) were considered significant at P ≤ 0.05. No differences in V160 (7.1 ± 0.2 m/s; 7.1 ± 0.2 m/s; P > 0.10), V180 (8.8 ± 0.2 m/s; 8.9 ± 0.2 m/s; P > 0.10), or V200 (10.6 ± 0.3 m/s; 10.7 ± 0.3 m/s; P > 0.10) were found between the racetrack and treadmill SET, respectively. Mean bias did not differ among V160 (−0.06 ± 0.35 m/s), V180 (−0.08 ± 0.35 m/s), and V200 (−0.06 ± 0.35 m/s; P > 0.10). Mean bias and percent total weight carried for each horse had strong negative correlations for V160 (r = −0.96; P < 0.001), V180 (r = −0.93; P < 0.01), and V200 (r = −0.83; P < 0.05). These results indicate that cardiovascular fitness measures obtained under saddle on a racetrack are reproducible when exercising on a treadmill with a 3° incline. Although overall differences between values obtained on the treadmill and racetrack were small, the individual horse variation was likely due to the percent of body weight carried while under saddle.

Springer, R.W., S. Dezalak, V.L. Erwin, I.N. Grayston, and J.D. Pagan. 2025. Comparison of cardiovascular fitness measures determined under saddle or on a high-speed treadmill. Journal of Equine Veterinary Science 148:105548.