A simple method for equine kinematic gait event detection

Summary Background Previous studies have validated methods for determining kinematic gait events using threshold‐based techniques. However, a simple method that can be successfully applied to walk, trot and canter is yet to be identified. Objectives To develop a simple kinematic method to identify the timing of hoof contact (hoof‐on), peak vertical force and lift off (hoof‐off), which can be applied in walk, trot and canter. Study design In vivo method authentication study. Methods Horses (n = 3) were ridden in walk, trot and canter down a runway on which four force plates were arranged linearly. Three‐dimensional forces were recorded at a sampling rate of 960 Hz and were synchronised with a 10‐camera motion analysis system sampling at 120 Hz. Events identified from vertical ground reaction force ( GRF z) data were hoof‐on (GRFz>50N), peak vertical force ( GRF z peak ) and hoof‐off (GRFz<50N). Kinematic identification of hoof‐on and hoof‐off events was based on sagittal planar angles of the fore‐ and hindlimbs. Peak metacarpophalangeal ( MCP )/metatarsophalangeal ( MTP ) joint extension was used to assess the time of GRFz peak . The accuracy (mean) and precision (s.d.) of time differences between kinetic and kinematic events were calculated for fore‐ and hindlimbs at each gait. Results Hoof‐off was determined with better accuracy (range: −3.94 to 8.33 ms) and precision (range: 5.43–11.39 ms) than hoof‐on across all gaits. Peak MCP angle (range: 5.83–19.65 ms) was a more precise representation of GRFz peak than peak MTP angle (range: 11.49–67.75 ms). Main limitations The sample size was small and therefore further validation is required. The proposed method was tested on a single surface. Conclusions This study proposes a simple kinematic method of detecting hoof‐on, hoof‐off and GRF z peak at walk, trot and canter. Further work should focus on validating the methodology in a larger number of horses and should extend the method for use on surfaces with varying levels of compliance.