Impact of discipline on fitness improvements in university horses

Evaluating equine fitness is crucial for optimizing training regimens and preventing injury caused by overwork. However, horses ridden by beginners often experience lighter workloads than those ridden by experienced riders, potentially increasing their risk of injury. This study aimed to (1) examine changes in fitness among university horses ridden by mixed-experience and experienced riders and (2) determine whether fitness levels vary by riding discipline. We hypothesized that horses ridden by beginners and experienced riders have lower fitness improvements compared with horses ridden by experienced riders and that fitness outcomes differ across disciplines. Adult horses (>3 yr; n = 17) of various breeds and minimal exercise in the past 3 mo were used in this study. Horse use was recorded, including rider experience, duration, and discipline. To evaluate fitness, horses performed a ridden standardized exercise test (SET) at the start and end of the study with the same experienced rider. Heart rate (HR), respiratory rate (RR), blood lactate (BL), and speed were recorded at each step of the SET. SETs included: 3 min walk, 2 min trot left, 2 min trot right, 2 min canter left, 2 min canter right, and 10 min walk. A Polar H10 hand-held monitor was used to measure HR. Respiratory rate was measured by watching the horse's flank. Blood lactate was obtained via jugular venipuncture and analyzed with a hand-held monitor (Lactate Plus, Nova Biomedical). Data were compared using a mixed model ANOVA with repeated measures (SAS 9.4). Horses exercised an average of 2 to 5 h/wk during the study. Horses were ridden by beginners and experienced riders (n = 9) or by only experienced riders (n = 8). Nine horses worked primarily in western and 8 horses worked primarily in English saddles. Average speed was not different between SETs (P = 0.088) and was 1.33, 2.93, 4.11, and 1.37 m/s for the walk, trot, canter, and cooldown, respectively. There was a SET by time interaction for HR (P = 0.022). After the canter step, HR was higher in SET 1 (102 ± 3 bpm) than in SET 2 (89 ± 3 bpm; P < 0.05). There was a main effect of SET on BL; BL was lower in SET 2 than in SET 1 (P = 0.0059). There was no difference in fitness parameters between disciplines or rider experience (P > 0.05). This study demonstrated that 11 wk of consistent, moderate exercise improved equine fitness, as evidenced by reduced heart rates and blood lactate levels during SETs. These findings highlight the effectiveness of regular training in enhancing fitness, regardless of the riding discipline, offering practical insights for equine management and training. The effect of high intensity, skilled work, or beginner-only riders requires further evaluation.