The objective of this retrospective study was to evaluate the physiological demands of cross-country competitions at different levels. Heart rates (HR) and post exercise blood lactate concentrations (LAC) measured between 2010 and 2019 in response to 1,463 cross-country competitions (437 at 2-star, 703 at 3-star, 313 at 4-star and 10 at 5-star level) in 294 horses were analysed. The effect of competition level, mean velocity, height profile, total distance, number of jumping efforts, climate, age, sex, percentage of Thoroughbred blood and performance level on HR, LAC, HR recovery and LAC disappearance rates was evaluated by Linear Mixed Effects Models. Mean HR and LAC significantly increased from 2-star to 4-star level (P<0.001). Each 30 m/min increase in mean velocity was associated with a 3 beats/min increase in HR (P<0.001) and a 41% increase in LAC (P<0.001) and each 30 m increase in cumulative elevation with a 2 beats/min increase in HR (P<0.001) and a 32% increase in LAC (P<0.001). Each 20 m increase in mean distance per jumping effort was associated with a 1 beat/min decrease in HR (P<0.01) and a 13% decrease in LAC (P<0.001). Compared to Warmbloods, horses with 75% Thoroughbred blood had 4 beats/min lower HRs (P<0.05) and 34% lower LAC values (P<0.001). Each 5 years increase in age was associated with a 4 beats/min decrease in HR (P<0.001, only in mares) and an 11% decrease in LAC (P<0.01). The HRs during the first 3 minutes of recovery were higher at warmer and more humid conditions (P<0.05). The rate of LAC disappearance was higher in horses with higher percentages of Thoroughbred blood (P<0.05).

Show jumping is a highly specialized equestrian discipline that requires technical skill but also power and fitness. Monitoring the horses’ aerobic performance is therefore essential in order to verify whether the training has induced the desired cardiovascular and muscular adaptations. This study therefore aimed at evaluating the validity of non-specific and discipline-specific field exercise tests for objective evaluation of aerobic performance in show jumpers. For this purpose, data obtained from horses competing at Junior and Young Rider level during show jumping competitions as well as field exercise tests were retrospectively analyzed. The effect of the level of difficulty, the horses’ age, the penalty score and the horses’ previous level of performance on blood lactate concentrations after show jumping competitions (100 observations in 49 horses) was evaluated by linear mixed effects models (horse as random effect). Estimated marginal means significantly increased from 140 (4.1 mmol/L) to 150 cm (5.2 mmol/L) classes (P = 0.02). Furthermore, post-exercise lactate values significantly increased with the horses’ age (P = 0.001). Another group of 12 horses performed a standardized incremental field exercise test on a track (SETtrack), a standardized show jumping course (SETcourse) and a standardized grid exercise (SETgrid) each on three consecutive days. Indices of aerobic performance, derived from the SETtrack [velocity at a heart rate of 140 bpm (V140) and at a lactate concentration of 2 mmol/L (VLa2)] were highly correlated with heart rate (V140: r = −0.75, P = 0.005; VLa2: r =−0.66, P = 0.02) and lactate (V140: r = −0.73, P = 0.02; VLa2: r = −0.72, P = 0.02) in response to SETcourse as well as heart rate during SETgrid (V140: r = −0.73, P = 0.02; VLa2: r = −0.76, P = 0.01). Subjective rating of muscular fatigue was significantly correlated to the mean heart rate during SETcourse (r = −0.64, P = 0.05) and SETgrid (r = −0.74, P = 0.02) but not to the aerobic indices calculated from SETtrack. Besides non-specific incremental field tests, performance monitoring in show jumpers should therefore also include discipline-specific tests that more closely reflect the internal load induced by show jumping competitions.