Stride frequency derived from GPS speed fluctuations in galloping horses

Area of Science:

• Equine biomechanics
• Sports science
• Veterinary orthopedics

Background:

• Stride parameter changes precede Thoroughbred racehorse injuries.
• Accurate quantification of stride parameters is crucial for large-scale injury research.
• Existing methods may require validation for widespread use in equine studies.

Purpose of the Study:

• To describe and validate a novel Fast Fourier Transformation (FFT)-based method for calculating stride frequency (SF) using GPS-logger data.
• To compare SF values derived from GPS-loggers with those from inertial measurement unit (IMU) pitch data.
• To assess the suitability of the GPS-based method for injury prevention research in galloping horses.

Main Methods:

• Twelve Thoroughbred horses were equipped with synchronized GPS-loggers and IMU-loggers attached to their saddlecloths.
• Horses performed gallop trials at approximately 16.1 m/s on a dirt racetrack.
• Stride frequency was extracted from GPS speed fluctuations using FFT and compared against IMU pitch data.

Main Results:

• The GPS-derived SF method showed good agreement with IMU-derived SF, with a bias of 0.0032 Hz and precision of +/-0.027 Hz.
• The precision of SF measurements across 100m gallop sections (0.0091 Hz) translates to stride length uncertainty smaller than injury-associated changes.
• The validated GPS method is suitable for calculating fundamental stride parameters.

Conclusions:

• A GPS-logger-based FFT method provides a reliable and accessible tool for measuring stride frequency in galloping horses.
• This technology can aid in the early detection of subtle stride alterations potentially related to musculoskeletal injury.
• The findings support the use of this method in large-scale studies for equine injury prevention strategies.