Maximum permissible load weight of a Taishuh pony at a trot

The aim of this study was to determine the loading capacity of a trotting Taishuh pony by gait analysis using a motion analysis system. Seven Taishuh Ponies (5 mares and 2 geldings) and their rider were fitted with a marker (70 mm in diameter placed on their chest) and recorded by 2 high-resolution digital DVD cameras (at a sampling frequency of 60 Hz) as they were trotting along a straight course. Each horse performed 7 tests: 1 test with a loaded weight of 70 kg, 5 tests with random loaded weights between 80 kg and 120 kg, and a final test with a loaded weight of 70 kg again. Three-dimensional movements of each marker were analyzed using motion capture system. The time series of the vertical displacements of the marker was subjected to spectrum analysis by the maximum entropy method, and the autocorrelation coefficient was calculated. The first 2 peaks of the autocorrelation were defined as symmetry and regularity of the gait, and the sum of symmetry and regularity was defined as stability. The cross-spectrum analysis (Blackman-Tukey method) also was performed to analyze the time lag and cross-correlation coefficient between the time series of both pony and rider. Among ponies, symmetry in the 120 kg test (0.54) was significantly lower than that in the first 70 kg test (0.75, P < 0.05) and stabilities in the 100 kg (1.17) and 120 kg (1.17) tests were significantly less than that in the first 70 kg (1.46, P < 0.05). Regarding the rider, there were no significant differences in symmetry, regularity, and stability between loaded weights. The time lag between the time series of horse and rider in the 120 kg test (47.6 ms) was significantly greater than that in the first 70 kg (14.3 ms, P < 0.05) test. These results suggests that the maximum permissible load weight of the Taishuh pony trotting at 3.0 m/s over a short distance was less than 100 kg, which is 43% of the BW.