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Author Young, L.E.; Rogers, K.; Wood, J.L.N. doi  openurl
  Title Left ventricular size and systolic function in Thoroughbred racehorses and their relationships to race performance Type Journal Article
  Year 2005 Publication Journal of Applied Physiology (Bethesda, Md. : 1985) Abbreviated Journal J Appl Physiol  
  Volume 99 Issue 4 Pages 1278-1285  
  Keywords *Adaptation, Physiological; Aging/physiology; Animal Husbandry; Animals; *Echocardiography; Female; Heart/*physiology; Heart Ventricles; Horses/*physiology; Male; *Physical Conditioning, Animal; Running/*physiology; Stroke Volume; Systole; Task Performance and Analysis  
  Abstract Cardiac morphology in human athletes is known to differ, depending on the sports-specific endurance component of their events, whereas anecdotes abound about superlative athletes with large hearts. As the heart determines stroke volume and maximum O(2) uptake in mammals, we undertook a study to test the hypothesis that the morphology of the equine heart would differ between trained horses, depending on race type, and that left ventricular size would be greatest in elite performers. Echocardiography was performed in 482 race-fit Thoroughbreds engaged in either flat (1,000-2,500 m) or jump racing (3,200-6,400 m). Body weight and sex-adjusted measures of left ventricular size were largest in horses engaged in jump racing over fixed fences, compared with horses running shorter distances on the flat (range 8-16%). The observed differences in cardiac morphologies suggest that subtle differences in training and competition result in cardiac adaptations that are appropriate to the endurance component of the horses' event. Derived left ventricular mass was strongly associated with published rating (quality) in horses racing over longer distances in jump races (P < or = 0.001), but less so for horses in flat races. Rather, left ventricular ejection fraction and left ventricular mass combined were positively associated with race rating in older flat racehorses running over sprint (<1,408 m) and longer distances (>1,408 m), explaining 25-35% of overall variation in performance, as well as being closely associated with performance in longer races over jumps (23%). These data provide the first direct evidence that cardiac size influences athletic performance in a group of mammalian running athletes.  
  Address (up) Centre for Equine Studies, Animal Health Trust, Newmarket, Suffolk, UK.  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 8750-7587 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:15920096 Approved no  
  Call Number Equine Behaviour @ team @ Serial 3768  
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