Cortisol release, heart rate and heart rate variability in the horse and its rider: Different responses to training and performance

Although some information exists on the stress response of horses in equestrian sports, the horse-rider team is much less well understood. In this study, salivary cortisol concentrations, heart rate (HR) and heart rate variability (HRV), SDRR (standard deviation of beat-to-beat interval) and RMSSD (root mean square of successive beat-to-beat intervals) were analysed in horses and their riders (n = 6 each) at a public performance and an identical rehearsal that was not open to the public. Cortisol concentrations increased in both horses and riders (P < 0.001) but did not differ between performance and rehearsal. HR in horses and riders increased during the rehearsal and the public performance (P < 0.001) but the increase in HR was more pronounced (P < 0.01) in riders than in their horses during the public performance (from 91 +/- 10 to 150 +/- 15 beats/min) compared to the rehearsal (from 94 +/- 10 to 118 +/- 12 beats/min). The SDRR decreased significantly during the equestrian tasks in riders (P < 0.001), but not in their horses. The RMSSD decreased in horses and riders (P < 0.001) during rehearsal and performance, indicating a decrease in parasympathetic tone. The decrease in RMSSD in the riders was more pronounced (P < 0.05) during the performance (from 32.6 +/- 6.6 to 3.8 +/- 0.3 ms) than during the rehearsal (from 27.5 +/- 4.2 to 6.6 +/- 0.6 ms). The study has shown that the presence of spectators caused more pronounced changes in cardiac activity in the riders than it did in their horses. (C) 2013 Elsevier Ltd. All rights reserved.