Influence of exercise on movement symmetry in Shetland ponies.

Abstract

Abstract Background and Aim: The locomotor system can be influenced by all types of exercise. Extensive research on the influence of exercise on the locomotor system has been done, mainly focusing on specific parts of the musculoskeletal system. Less research has been done on the influence of exercise on the symmetry of the horse as a whole. This study examined the influence of exercise protocols on the symmetry of Shetlandponies. The aim was to evaluate changes in locomotion symmetry of locomotion patterns during a period of daily exercise in Shetland ponies, using optical 3D motion capture.

Methods: Two types of training protocols are tested in a group of six Shetlandponies. To measure the parameters, reflective markers were attached to the skin on the head, withers and pelvis. Gait analysis was performed in the first week and in the fourth week of both protocols. Measured parameters were: minimum height differences (mindiff), maximum height differences (maxdiff) and vertical movement amplitude differences (range-up) of the head, withers and pelvis. Further, the range of motion of the carpus joint of both front limbs were measured.

Results: Most symmetry parameters decreased in both protocols. In protocol A, this was significant in walk for maxdiff of the head (-3.40 mm), for range-up of the withers (-1.71 mm) and for pelvis range-up (1.89 mm). In trot it was significantly for head range-up (-3.00 mm), for mindiff of the withers (-1.30 mm) and for pelvis maxdiff (-1.24 mm) and range-up diff (1.09 mm). In protocol B symmetry parameters changed significantly in walk for head range-up (-5.64 mm), for withers mindiff (-1.69 mm), maxdiff (-0.96 mm) and range up (1.35 mm) and for pelvis range up (-2.15 mm). In trot it was significant for head maxdiff (-1.52 mm) and range-up (-1.57 mm), for withers maxdiff (-0.70 mm) and range up (2.87 mm) and for pelvis mindiff (-1.44 mm) and maxdiff (-0.96 mm). However, only symmetry parameter differences of 2.5 mm and more were considered clinically relevant. The range of motion of the carpus and front limbs decreased most in protocol A and less in protocol B. The difference in range of motion between the left and right limb decreased after training in both protocols.

Conclusion: Small changes in locomotion symmetry were detected in Shetland ponies after 4 weeks of training. These changes could be related to the ponies getting fitter, but also to a more efficient way of treadmill exercising, which the ponies were able to learn after 4 weeks of training.