Is the Movement of the Thoracolumbar and Lumbosacral Joints in the Ridden Dressage Horse Affected by Muscle Development?

Abstract

IntroductionStabilisation of the back is essential for rider support and to moderate intervertebral movement. Epidemiological data has shown that 25% of UK dressage horses had back pain over a 2‐year period (Murray et al. ). It has been established that back pain in sports horses is performance limiting (Stubbs et al. ). Intervertebral range of motion (ROM) and flexion–extension movements of the back have been previously described. However, the relationship between muscle development and ridden ROM has not been investigated.AimsTo investigate the relationship between grade for development of muscles visible on examination and ridden ROM of the thoracolumbar (TL) and lumbosacral (LS) regions of the back.MethodsThirty‐five dressage horses (novice to Grand Prix competition level) were evaluated by an experienced clinician and assigned muscle development grades. High‐speed motion‐capture (250Hz) was used to measure TL and LS angle for 4 strides of collected trot from the left side. Spearman's rank correlation tests were used to test for associations between muscle development grade and ridden angles and ROM.ResultsIncreased development of visible muscle groups was correlated with increased TL and LS flexion at different parts of the stride (Table ). Decreased LS ROM was associated with increase muscle development of the thoracic and lumbar regions.Conclusions and practical significanceResults suggest that increased development of muscle groups visible on examination is important for stabilising the TL and LS regions. Back stabilisation is likely to help support the rider's weight and be involved in protection of the small joints and ligaments of the back. These findings support evaluation of the musculature during a veterinary examination as a guide to TL and LS stability, and the potential importance of visible muscle development in prevention and rehabilitation of ridden back problems.Ethical animal researchStudy approved by AHT Ethical Review Committee. Sources of funding: Funding from the Elise Pilkington Charitable Trust, British Dressage and Dr Wilfrid Bechtolsheimer. Competing interests: None. Table summarising association of muscle development grade with back angles at specific points of the stride within the hindlimb (HL) and forelimb (FL) Angle Point of stride Muscle group Thoracolumbar (TL) HL stance Lumbosacral, pelvic HL maximum protraction Neck, lumbar, lumbosacral, pelvic FL stance Neck, lumbar, lumbosacral, pelvic Lumbosacral (LS) HL stance Abdominal, thoracic, lumbar, lumbosacral, pelvic, hindlimb HL maximum protraction Abdominal FL stance Abdominal, lumbosacral, hindlimb