Back motion in unridden horses in walk, trot and canter on a circle

Abstract

Equine back function is of concern to riders, as well as to veterinarians and physiotherapists; these groups may benefit from knowledge about spinal motion on the circle. This descriptive and comparative study aimed to quantify equine neck, back and pelvic motion in walk, trot and canter on a 9 m circle. Sixteen healthy horses in training, of varying breed and conformation, were measured using optical motion capture (150 Hz), with optical markers on the poll, withers, T15, tubera coxae and lumbosacral joint. Cervicothoracic and thoracolumbar flexion–extension and lateral bending, and pelvic roll, pitch and yaw, were statistically evaluated using mixed models. Motion patterns showed distinct differences between gaits, but were generally similar between horses. The thoracolumbar back was bent towards the inside of the circle (stride mean 5-6º for all gaits). The cervicothoracic spine was more flexed in walk (18°), and more extended in canter (-4—-8°), compared to trot (6–7°), whereas the thoracolumbar spine was slightly less extended in canter than in walk. Thoracolumbar flexion–extension range of motion (ROM) increased from walk (4°) to canter (9°), as did pelvic pitch ROM (walk 7° and canter 15–16°), while back lateral bending ROM and pelvic yaw ROM were lowest in trot. Taken together, the study findings suggest that neck and back motion patterns on the circle reflect an interaction between the constraints of circular movement, and the mechanics and characteristics of each gait.

A Method for Quantifying Back Flexion/Extension from Three Inertial Measurement Units Mounted on a Horse’s Withers, Thoracolumbar Region, and Pelvis

“…During galloping, our results showed a mean range of flexion of 9.5° (±1.3°) and a mean range of extension of 9.8° (±1.4°) in a large circle in the left rein. These results are consistent with the results of Egenvall et al (2022) [ 15 ], who found a mean range of flexion/extension of 9.2° in the same conditions [ 15 ]. These converging results with MOCAP allow us to compare our IMU results to the MOCAP results, which could be considered a reliable reference.…”

“…Other studies measured the flexion and extension ranges of motion in vivo using a motion capture system (MOCAP) [ 1 , 5 , 13 , 14 , 15 ]. These studies showed flexion/extension ranges of motion of approximately 4° between T6, T13, and T18 while trotting in a straight line on a hard surface [ 1 ]; 4.91° and 4.97° between the withers, T15 and the pelvis, while trotting in a straight line on hard and soft surfaces, respectively [ 5 ]; 3.07° at T17 (rotation around the mediolateral axis of the T17 markers) during trotting in a straight line on a hard surface [ 13 ]; and 2.9° between T13, T18, and the pelvis during trotting in a straight line on a hard or soft surface [ 14 ].…”

“…These studies showed flexion/extension ranges of motion of approximately 4 • between T6, T13, and T18 while trotting in a straight line on a hard surface [1]; 4.91 • and 4.97 • between the withers, T15 and the pelvis, while trotting in a straight line on hard and soft surfaces, respectively [5]; 3.07 • at T17 (rotation around the mediolateral axis of the T17 markers) during trotting in a straight line on a hard surface [13]; and 2.9 • between T13, T18, and the pelvis during trotting in a straight line on a hard or soft surface [14]. Recently, a study showed flexion/extension ranges of motion of 3.86 • and 4.05 • during walking, 5.96 • and 5.66 • during trotting, and 9.15 • and 9.17 during galloping between the withers, T15, and the pelvis in a circle, respectively, at the left and right rein on a soft surface [15]. MOCAP allows the monitoring of these spatiotemporal events [16], including thoracolumbar angle evolution [5].…”

Pilot study of locomotor asymmetry in horses walking in circles with and without a rider

“…Scripts were written in Matlab (version R2020a; Mathworks, Natick, MA, USA) for analysis of kinematic data, producing time-series variables (see below). Data were processed as previously described in Egenvall, Engström & Byström (2023) . In short, circle radius was determined for each measurement (trial) through fitting a circle to the x and y (horizontal plane) coordinate data from the lumbosacral joint marker using the least squares method.…”

“…Hind limb maximum protraction was then identified. The kinematic variables were time-normalised to 0–100% (201 values per stride) before extraction of data for statistical analysis ( Egenvall, Engström & Byström, 2023 ).…”