Circular exercise is used frequently in equine exercise and competition, but little is known of the impact circular diameter and gait have to the joint and bone health of the forelimb. The first study evaluated the impact of circle diameter (10-m and 15-m) and gait to the forelimb solar outputs of average surface area, vertical force, and average pressure. Nine horses exercised in a straight line and in a round pen while wearing the Tekscan Hoof SystemTM on both front hooves with a glue-on shoe, a method of adherence which was determined to be reliable when measurements were recorded within one session. Gait, and not circle diameter, impacted forelimb outputs, with the average loaded area of the outside hoof while circling, being greatest at the canter (P = 0.001). While exercising on both a large and small circle, the outside hoof had greater vertical force at the canter than the trot (P = 0.01). A second study utilizing calves as a model for juvenile horses allowed the determination of physiological responses to circular exercise. Calves were assigned to small circle exercise (12 m), large circle exercise (18 m), treadmill exercise, or non-exercised control treatments (n = 6). Computed tomography and biomarkers were evaluated to determine impacts to bone and joint health. The inside leg of the small circular exercise group had larger dorsopalmar external diameter than the outside (P = 0.05). The medial proximal phalanx had greater mediolateral diameter than the lateral proximal phalanx of the small circle group (P = 0.01). Cartilage glycosaminoglycan concentration was greater in the outside leg of the small circle exercise treatment than the inside leg (P = 0.03). Combined, both of these studies suggest that circular exercise diameter and gait can impact animal health and should be considered when performing circular exercise.
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