BRIEF REPORT Center-of-Pressure Movements During Equine-Assisted Activities Hilary M. Clayton, LeeAnn J. Kaiser, Bonnie de Pue, Lana Kaiser KEY WORDS  cerebral palsy  equine-assisted therapy  motion  postural balance  pressure We compared anteroposterior and mediolateral range of motion and velocity of the center of pressure (COP) on the horse’s back between riders without disabilities and riders with cerebral palsy. An electronic pressure mat was used to track COP movements beneath the saddle in 4 riders without disabilities and 4 riders with cerebral palsy. Comparisons between rider groups were made using the Mann–Whitney test (p < .05). The two rider groups differed significantly in anteroposterior range of COP motion, mediolateral range of COP motion, and mediolateral COP velocity. Anteroposterior COP velocity did not differ between groups. The results suggest that measurements of COP range of motion and velocity are potentially useful for monitoring changes in balance as an indicator of core stability during equine-assisted activities. Clayton, H. M., Kaiser, L. J., de Pue, B., & Kaiser, L. (2011). Brief Report—Center-of-pressure movements during equine- assisted activities. American Journal of Occupational Therapy, 65, 211–216. doi: 10.5014/ajot.2011.000851 Hilary M. Clayton, PhD, DACVSMR, MRCVS, is Mary Anne McPhail Dressage Chair in Equine Sports Medicine and Professor of Large Animal Clinical Sciences, Mary Anne McPhail Equine Performance Center, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824; claytonh@cvm.msu.edu LeeAnn J. Kaiser, MS, is Laboratory Manager, Mary Anne McPhail Equine Performance Center, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing. Bonnie de Pue, OTR, is President, Children and Horses United in Movement (C.H.U.M.) Therapeutic Riding, Dansville, MI. Lana Kaiser, MD, DVM, is Professor of Nursing and Medicine, Department of Medicine, College of Human Medicine, Michigan State University, East Lansing. E questrian sports require the ability to stabilize the rider’s trunk in the face of perturbations provided by translations and rotations of the horse’s body. Because the three-dimensional movements of the horse’s back resemble those of human gait (Riede, 1988), riding provides people with cerebral palsy with a novel sensorimotor experience that simulates pelvic motion during ambulation. The term cerebral palsy is used to de- scribe a group of permanent disorders of the development of movement and posture that cause activity limitation and that are at- tributed to nonprogressive disturbances that occurred in the developing fetal or infant brain (Rosenbaum et al., 2007). The Gross Motor Function Classification System (GMFCS; Palisano et al., 1997) is a method of grading the severity of impairment of people with cerebral palsy. Grades I and II include people who are able to walk without assistance, whereas people in Grades III–V have increasingly limited self-mobility. Peo- ple who are more severely affected may also lack strength in their core musculature and, consequently, have poor control of their trunk movements. The rhythmic movements of the horse during equine-assisted activities are thought to improve co-contraction, joint stability, weight shift, and postural and equilib- rium responses in people with cerebral palsy (Bertoti, 1988). The responses to ther- apeutic riding have been reported to include improvements in standing posture (Bertoti, 1988); in the walking, running, and jump- ing scores on the GMFCS Dimension E (McGibbon, Andrade, Widener & Cintas, 1998); and in dynamic postural stabiliza- tion, the ability to recover from perturba- tions, and anticipatory and feedback postural control (Sterba, 2007). Moreover, beneficial changes in trunk and head sta- bility and reaching and targeting recorded after a 12-wk course of therapy were re- tained for at least 12 wk (Shurtleff, Standeven, & Engsberg, 2009). The GMFCS has proven to be a valid and reliable method of classifying people with cerebral palsy on the basis of their mobility, but the grading criteria used are not related specifically to activities that would be expected to improve in response to therapeutic riding. Other methods of measuring the response to therapeutic rid- ing in a manner that is both standardized and specific to the task should be developed (Pauw, 2000). In this study, we investigated the potential value of one such method that The American Journal of Occupational Therapy 211 Downloaded From: http://ajot.aota.org/ on 11/09/2018 Terms of Use: http://AOTA.org/terms