Validation of a Three Dimensional Motion Capture System for Use in Identifying Characteristics of the Running Walk

Validation of a Three Dimensional Motion Capture System for Use in Identifying Characteristics of the Running Walk

A three-dimensional (3-D) motion capture system was adapted for use in characterizing the biomechanics of the Running Walk, a stepping gait of the Tennessee Walking Horse (TWH) breed. Registered TWH (n = 4) were ridden through an arrangement of high-speed digital cameras at the walk (W) and running walk (RW). Infrared reflective markers (65 per horse) were used to track body segments and joint centers. Five trials per gait per horse were recorded. A dynamic 3-D model was created and used to label and track body segments. Temporal stride characteristics and joint angle values were extracted by a custom script file and gait formulas were calculated for each gait per horse. Temporal stride characteristics and gait formulas of both W and RW were found to be similar to those previously reported. Overstride (OS), which has not previously been described, increased from W to RW (P < 0.0001). The increase in OS accounted for 96% of the increase in stride length; only 4% of the increase in stride length is due to an increase in step length. OS was positively correlated to velocity and stride length (P < 0.0001), and negatively correlated to front stance duration, hind stance duration and total stance duration (P < 0.0001). A long OS would appear to be related to the flexibility of the proximal hind limb, the pelvis and possibly the lumbar spine. Hind stance duration as a percent of total stride time, advance placement as a percent of total stride time, and advance liftoff as a percent of total stride time did not differ between W and RW (P > 0.05), suggesting that the RW is not simply a faster version of W. 3-D analysis allowed for thorough analysis of joint angles. The joint angles of the carpus were highly correlated to stride length, OS, and advance placement (P < 0.0001), but were not correlated to velocity (P > 0.05). These joint angles and gait events can be viewed as velocity-independent stride characteristics and may be suitable for making comparisons between horses traveling at different velocities. Identification of joint-specific velocity-independent stride characteristics may enhance our ability to associate lameness with an individual joint.

KEYWORDS
horse
gait
biomechanics