How does trotting over ground and raised poles alter equine spinal kinematics?

Background: To enhance limb range of motion (ROM), polework exercise is routinely used in equine training and rehabilitation programmes; however, limited data exist on the effect that polework exercise has on the flexion-extension of the thoracolumbar spine.

Objectives: To quantify flexion, extension, and total ROM of the thoracolumbar spine when trotting in-hand over 10 cm ground poles (GP) and 26 cm raised poles (RP) compared to no poles (NP).

Study design: Experimental.

Methods: Reflective skin markers (19 mm) were placed on the midline of 32 riding horses at thoracic (T) T6/T10/T13/T15/T17, lumbar (L) L1/L3/L5 vertebrae. Ten optical motion cameras (240 Hz) captured three passes of in-hand straight line trotting over NP, five GP and five RP with distances set to 100% of horse's forelimb step length. Flexion, extension and total ROM of T10/T13/T15/T18/L2/L4 were calculated and analysed using repeated-measures ANOVA with an adjusted p-value (p < 0.01).

Results: Trotting in-hand over poles increased total ROM at T10/T13/T15/T18/L2/L4 (all < p = 0.001). The thoracic spine was more extended when trotting over GP and RP compared to NP at T10 (NP:18.64±2.81°, GP:19.68±2.91°, RP:21.20±3.21°, p = 0.008), T13 (NP:12.76±3.07°, GP:14.25±3.23°, RP:15.18±3.90°, p < 0.001), T15 (NP:1.29±2.07°, GP:2.63±2.24°, RP:3.26±2.68°, p < 0.001). Increased extension of the thoracolumbar spine occurred for the RP vs. GP at T10 (p = 0.008) and T13, T15, T18, L2, L4 (all p < 0.001). Maximal thoracolumbar flexion decreased over GP and RP, compared to NP, at T10 (NP:14.28±2.92°, GP:12.61±3.04°, RP:12.65±3.66°, p < 0.001 for both), T13 (NP:9.05±3.30°, GP:7.99±3.20°, RP:7.38±3.68°, p < 0.001 for both) and RP only at T15 (NP:-1.34±2.23°, RP: −2.31±2.39°, p ≤ 0.001).

Main limitations: Only in-hand trotting with free head–neck position studied.

Conclusions: Trotting over poles increases spinal mobility, which may be desirable for training and rehabilitation; however, care should be taken if thoracic spinal extension is contraindicated. Raised poles induce greater ROM changes than GP and increase extension of the lumbar spine, all of which should be considered when prescribing polework exercise.