INNOVATIVE MOTION PRODUCTS ETB Pegasus equipment was used in the following paper Validation of a Novel Accelerometer-GPS system for measuring stride characteristics in galloping horses JRJ Naylor and DJ Holmes * Naylor-Racing and University of Bristol, Dept of Anatomy *University of Bristol, Dept of Clinical Veterinary Science European Technology for Business Ltd, Codicote Innovation Centre, St. Albans Road, Codicote, Herts SG4 8WH, UK Tel: +44 (0)1438 822822 Web: www.etb.co.uk
Validation of a Novel Accelerometer-GPS system for measuring stride characteristics in galloping horses DJ Holmes* and JRJ Naylor *University of Bristol, Dept of Clinical Veterinary Science Naylor-Racing and University of Bristol, Dept of Anatomy
Introduction Methods for equine stride measurement - Optical gait analysis systems - Instrumented shoes - Accelerometer devices
Aims To validate the new Pegasus system against a standard method To examine the reliability and practicality of the Pegasus system in making stride measurements on Thoroughbred racehorses in training
Materials and Methods Pegasus System data were collected using a Pegasus triaxial accelerometer/data logger (European Technology for Business Ltd) - measuring 78 x 25 x 10mm - weighing 52g A proprietary GPS receiver/data logger (GL-50-S, San Jose Navigation Inc) - measuring 62 x 40 x 25mm - weighing 79g Units were synchronised before data collection with custom software, Poseidon (ETB Ltd) After collection, data were downloaded to personal computer for processing by Poseidon software which returned elapsed time, gait, SF, SL, speed and temperature at 1 Hz
18 3 16 14 Speed Length Str i de Rate 2.5 12 2 10 8 1.5 6 1 4 2 0.5 0 0 08:05 08:10 08:15 08:20 T i me ( hr : mm)
Horses 6 fit Thoroughbred racehorses were used - 4 mares and 2 geldings aged 2-7 years Experimental Protocol Horses exercised in pairs, twice on a 1200m (6 furlong) wood chip all-weather gallop Riders rode constant speeds using speed/heart rate monitors at 11 ms ¹ (25 mph) and 16 ms ¹ (36 mph) on first and second runs, respectively
Stride data from Accelerometer-GPS system were compared with manual measurements Manual SL was measured between successive imprints of the lead fore foot between the third and fourth furlong marker Manual timing was measured using a stopwatch
Statistics Extent of agreement of SL and SF between methods was compared using analysis of Bland and Altmann 1986 Paired t tests where applicable (significance P<0.05) Stride regularity was compared examining coefficient of variation for SL and SF for each run (Dubost et al, 2008)
Results Mean speed for 6 horses 0.11 0.06 p 16.02 15.77 11.52 11.33 Mean 15.97 15.87 11.34 11.31 6 15.97 15.87 11.36 11.31 5 15.70 15.09 11.94 11.66 4 15.80 15.09 12.19 11.66 3 16.36 16.34 11.12 11.03 2 16.33 16.34 11.15 11.0 1 Pegasus Manual Pegasus Manual Horse 16m/s 11m/s
SL agreement between methods 0.075 Difference in SL by two methods (m) 0.055 0.035 0.015-0.005 5 5.5 6 6.5 7-0.025 Mean difference Mean SL by tw o methods (m) Mean Difference +/- 2sd Mean difference between methods for SL was 0.026m - Represents 0.43% difference (mean SL by two methods is 6.08m)
SF agreement between methods 0.16 0.14 Difference in SF by two methods (Hz) 0.12 0.1 0.08 0.06 0.04 0.02 0 1.99-0.02 2.04 2.09 2.14 2.19 2.24 2.29 2.34 2.39 2.44-0.04-0.06 Mean SF by tw o methods (Hz) Mean difference Mean Difference +/- 2sd Mean difference between methods for SF was 0.047 Hz - Represents 2.10 % difference (mean SF by two methods is 2.234Hz)
Within-run SL coefficient of variation 11m/s 16m/s No significant differences in either run Horse 1 2 Manual 1.68 1.38 Pegasus 1.47 1.40 Manual 2.20 3.14 Pegasus 2.16 3.62 3 2.08 1.15 1.96 2.57 4 2.22 1.85 2.00 1.70 5 1.88 2.30 2.32 0.74 6 2.47 2.14 2.80 1.60 Mean 1.95 1.72 2.40 2.07 p 0.26 0.40
Conclusion Data were consistent with previous reports Very close agreement between methods Important source of error was most likely manual timing Within-run stride variability was the same for both methods Pegasus system was accurate, reliable, robust and repeatable in field conditions Will allow for future application for further research questions
References Barrey, E., Evans, S.E., Evans, D.L., Curtis, R.A., Quinton, R. and Rose, R.J. (2001) Locomotion evaluation for racing in thoroughbreds. Equine Veterinary Journal Supplement 33, 99-103. Bland, J. and Altman, D. (1986) Statistical methods for assessing agreement between two methods of clinical measurement Dubost, V., Annweiler, C., Aminian, K., Najafi, B., Herrmann, F.R. and Beauchet, O. (2008) Stride-to-stride variability while enumerating animal names among healthy young adults: Result of stride velocity or effect of attention-demanding task. Gait & Posture 27, 138-143.