Specificity and variability of trunk kinematics on a mechanical horse

Abstract

As perturbation training is gaining popularity, it is important to better understand postural control during complex three-dimensional stimuli. One clinically relevant and commonly used threedimensional stimulus is found in hippotherapy and simulated hippotherapy on a mechanical horse. We tested nine healthy participants on a horse simulator, measured head and trunk kinematics, and characterized data in time (root-mean-square and variability) and frequency (amplitude spectra, gains, and phases) domains. We addressed three fundamental questions: 1) What is the specificity of postural responses to the simulator? 2) Which plane of motion is associated with the most and least variability (repeatable movements across repeated stimuli and across participants)? 3) To what extent are postural responses influenced by different degrees of stability (addition of pelvis straps and trunk support)? We found head and trunk responses were highly specific to the threedimensional simulator perturbation direction and frequency. Frontal plane responses had the least variability across repetitions and participants whereas transverse motion was most variable. Head motion was more variable that the trunk at low frequencies and exhibited a marked decrease in tilt in the sagittal plane. Finally, the inclusion of pelvis straps had minimal effect on kinematics at low frequencies but altered higher frequencies; whereas added trunk support reduced head and trunk responses to perturbations and altered timing characteristics in all three planes. In conclusion, the present study suggests that frontal plane motion was under a high level of control, and results support the idea that specific head and trunk postural responses can be elicited from a complex three-dimensional stimuli, such as those found in hippotherapy. Researchers and clinicians can use results from this study to help interpret variability, implement mechanical adjustments to stability, and assess responses in pathological populations.

Analysis of trunk muscles activity during horseback riding machine exercise in children with spastic cerebral palsy

“…[15] In order to make up for such limitations while retaining the advantages of horseback riding, some attempts have been made to incorporate a real horse-like horseback riding machine into clinical practice. [16] Various horseback riding machines were developed to allow people to take horseback riding exercise indoors, most of the studies on horseback riding machine exercise have investigated the enhancement of balance and walking ability in children with intellectual disability. [17][18][19] However, there have been no studies on the activity of trunk muscles in children with cerebral palsy during horseback riding machine exercise.…”

Analysis of Trunk Neuromuscular Activation During Equine-Assisted Therapy in Older Adults

“…The rider needs to keep the head up, shoulders aligned and level, and arms relaxed. To maintain this balanced position, reflex contractions of the agonist and antagonist muscles are necessary throughout the body, including the muscles of the head, neck, and trunk (Goodworth et al, 2019). The trapezius is a superficial muscle that is easily recruited during many movements of the head and shoulders (Cheng et al, 2016).…”

Effects of Equine-Assisted Therapies or Horse-Riding Simulators on Chronic Pain: A Systematic Review and Meta-Analysis

“…Horse-riding simulators have emerged as an alternative for real horse riding since they could provide a comparable pattern of stimuli which can lead to specific postural responses [ 39 ]. It must be noted that this type of therapy could have some objectives advantages [ 21 ], involving lower costs due to the maintenance of the machine is cheaper than the costs associated with caring and training the horses.…”