127 Quantification of frequency, amplitude, and transmission from equine whole body vibration platform

Abstract

Whole body vibration (WBV) is commonly utilized across the equine industry, yet a lack of standardization in vibration platforms and vibrational transmission across the equine body has made interpretation of results across studies difficult. Furthermore, vibrational transmission across the equine body is poorly understood and is a key consideration when interpreting the effects of WBV. This work quantifies vibration platform output despite the ambiguous metrics associated with plate input, establishes normative values for transmission to various equine tissues, and demonstrates criterion future equine WBV studies should consider measuring and reporting as part of their study. Baseline measurements of frequency and amplitude were taken using triaxial accelerometers on a vibration platform (TheraPlate, Weatherford, Texas) without a horse at the 20%, 50%, and 80% input levels. A horse was subsequently placed on the vibration platform with one accelerometer placed on the front left hoof, and a second accelerometer placed on the left cannon bone, withers, sacrum, and left back hoof at each input level measured. The maximum frequency (64.2 Hz) associated with the maximum amplitude (20.69 m/s2) of vibration was found to be stable within input levels at each anatomical part of the horse in comparison to the hoof, with relative differences from 0% to 0. 94%. As expected, the frequency associated with themaximum amplitude increased as the input levels increased from 20% to 50% and 80%. Peak acceleration amplitude was more variable but exhibited consistent attenuation as the accelerometer increased in distance from the vibration platform. The greatest attenuation observed was at the withers, which was 16.25 m/s2 to 0.07 m/s2 from hoof to withers, respectively. A maximal value in amplitude of 17.76 m/s2 was observed at the 50% input level with no further resonant peaks before the 80% input level. Therefore, increasing the input level beyond 50% does not guarantee that the amplitude of vibration will increase. A reduction in amplitude experienced in the equine body dorsal to the extremities indicates that vibration transmission is greatly attenuated and may not be effective in eliciting a physiological response higher up on the body. The similarity of baseline vibration platform input to the measurements with a horse present indicates a horse on the platform does not greatly impact the equipment's performance. Future studies in equine WBV should consider reporting at minimum platform frequency and amplitude in addition to vibrational transmission to equine anatomical parts of interest.