de la Guérinière was right: shoulder-in is beneficial for the physical and mental states of horses

Abstract Lateral exercises are commonly practiced in equitation. Studies on the influence of these exercises on horses’ emotional responses are scarce. This study investigated equine behavioral and physiological responses to lateral exercises. Forty horses (11±4 years old) and two riders (one professional and one amateur) were involved in the research. Two sessions of approximately 10 minutes each were performed. In session 1, longitudinal exercises were performed at three gaits: walk, trot and canter. In session 2, horses performed a lateral exercise (shoulder-in) at the three gaits. To study autonomic nervous system activity, heart rate variability was assessed using heart rate (HR), low-frequency/high-frequency ratio (LF/HF) and very-low-frequency (VLF) data. Behaviors previously associated with a horse’s lack of attention (looking around frequency – LAF) and relaxation (playing with/chewing the bit duration – PCB) were collected. LAF was significantly highest in session 1 (p