Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 5. Kinematic effects.
OBJECTIVE
To examine the effect of race training on kinematic parameters of the trot in a sample of 2-year-old Thoroughbred fillies.


METHODS
Two-year-old Thoroughbred fillies that had been either trained for racing (n=7) or left untrained in small paddocks (n=7) were examined for lameness, and linear and temporal kinematic data were collected from video recordings of each horse trotted in-hand, 5, 9 and 13 weeks after the beginning of training. Horses were graded as: sound (Grade 0), suspected but not obviously lame (Grade 1), or definitely lame at the trot (Grade 2).


RESULTS
Mean velocity at the trot did not vary with lameness grade. Compared with horses classified as sound (Grade 0), horses classified as suspected or definitely lame (Grades 1 and 2) had shorter (2.55 (SE 0.02) vs 2.41 (SE 0.02) and 2.44 (SE 0.03) m; p<0.001) and faster (671 (SE 3) vs 645 (SE 1) and 647 (SE 4) msec; p<0.001) strides. None of the linear or temporal parameters measured varied significantly between the successive observation periods. When data from sound horses were pooled, the training group trotted at a higher mean velocity (4.22 (SE 0.08) vs 3.22 (SE 0.06) m/sec; p<0.001) and with a longer stride length (2.79 (SE 0.05) vs 2.18 (SE 0.06) m; p<0.001) than the untrained group. The stride duration was longer (669 (SE 7) vs 662 (SE 9) msec; p=0.01), stance period was shorter (34.1 (SE 0.6) vs 39.3 (SE 0.7) %; p<0.001) and mid-stance was achieved earlier in the stride (12.1 (SE 0.6) vs 13.1 (SE 0.2) %; p=0.001) in the trained than the untrained group. A longer swing phase in the trained group was associated with an increase in retraction time (9.2 (SE 0.2) vs 7.6 (SE 0.3) %; p=0.001).


CONCLUSIONS
These data indicate that early race training in young Thoroughbreds was associated with quantifiable changes in linear and temporal kinematic parameters of the trot, which were related to the race-training objective of improving the horse's ability to work at higher velocities.


CONCLUSIONS
Race training resulted in changes in the gait of non-lame horses at the trot, which should be considered during veterinary lameness examinations.
Rogers
C W
CW
Massey Equine, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand. C.W.Rogers@massey.ac.nz
Firth
E C
EC
Anderson
B H
BH
D000818:Animals; D001696:Biomechanical Phenomena; D001947:Breeding; D005260:Female; D005684:Gait / Q000502:physiology*; D006736:Horses / Q000502:physiology*; D007794:Lameness, Animal / Q000503:physiopathology; D009142:Musculoskeletal Physiological Phenomena; D010805:Physical Conditioning, Animal / Q000502:physiology*; D014741:Video Recording