Do Training Aids Affect the Kinematics of the Equine Thoracolumbosacral Spine when Being Lunged in Trot on a Circle?

Background: When lungeing is used as part of a training or rehabilitation programme, training aids (TA) are often fitted in the belief that they facilitate improved back and limb biomechanics leading to the development of increased core strength and spinal stability. 
Objectives: To quantify the effect of a Pessoa Training Aid (PTA), Side Reins (SR) and a Three Band System (TBS) designed to activate the musculature of the 1) cranial thoracic spine, 2) caudal thoracic spine and 3) hind quarters, on the kinematics of the thoracolumbosacral spine compared to no training aid (NTA). 
Study design: Quantitative observational. 
Methods: Skin mounted inertial sensors were glued on to the midline of the back of 10 non-lame sports horses at thoracic vertebrae T5, T13, lumbar vertebra L3, tuber sacrale TS and sacral vertebra S5. In a randomised order, horses were lunged on a 16 m diameter circle (left/right circle) wearing a PTA, SR and BS or without TA. Differential rotational movement between adjacent sensors (40 motion-cycles per condition) were analysed using a general linear mixed model, with condition (TA, direction) as fixed factors and horse as random factor (Bonferroni post hoc comparison, p < 0.05). 
Results: Mean (S.D.), compared to NTA no differences were found in pitch (flexion-extension) values at any location (All p =>0.07) for any TA. Roll (axial-rotation) decreased at T13-L3 (6.7°(0.6), p = 0.01) increased at L3-TS (20.6°(1.0), p = 0.01) for TBS compared to NTA (8.0°(0.6)/19.0°(1.0)). Yaw (lateral- bending) decreased at T13-L3 for TBS (5.1°(0.3), p =<0.001) and SR (6.7°(0.3), p =0.05) compared to NTA (6.9°(0.3)). 
Main limitations: Only circle data studied. 
Conclusions: There was no evidence to support the hypothesis that PTA alters thoracolumbosacral spinal kinematics. The reported decrease in rotational movement of the caudal thoracic/cranial lumbar region may be a sign of dynamic stability, as a function of the TBS activating the horse’s core musculature. This requires further investigations. 
Ethical animal research: Approved by the Royal Veterinary College ethics and welfare committee. Informed consent: Informed client consent was obtained for all animals. 
Competing interests: T. Pfau is owner of EquiGait Ltd providing gait analysis products and services. 
Sources of funding: Centaur Biomechanics.

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