Young L E, Rogers K, Wood J L N
Centre for Equine Studies, Animal Health Trust, Newmarket, Suffolk, UK.
J Appl Physiol (1985). 2005 Oct;99(4):1278-85. doi: 10.1152/japplphysiol.01319.2004. Epub 2005 May 26.
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.
众所周知，人类运动员的心脏形态存在差异，这取决于他们所从事项目的特定运动耐力成分，而关于心脏超大的超级运动员的轶事也屡见不鲜。由于心脏决定了哺乳动物的每搏输出量和最大摄氧量，我们开展了一项研究，以检验以下假设：训练有素的马匹的心脏形态会因比赛类型而异，且精英赛马的左心室尺寸最大。对482匹适合参赛的纯种马进行了超声心动图检查，这些马参加平地赛（1000 - 2500米）或障碍赛（3200 - 6400米）。与在平地上跑较短距离的马匹相比，参加固定围栏障碍赛的马匹经体重和性别调整后的左心室尺寸测量值最大（范围为8 - 16%）。观察到的心脏形态差异表明，训练和比赛中的细微差异会导致心脏适应性变化，以适应马匹比赛的耐力成分。在障碍赛中跑较长距离的马匹，其左心室质量与已公布的评分（质量）密切相关（P≤0.001），而在平地赛中的马匹相关性则较弱。相反，在参加短跑（<1408米）和较长距离（>1408米）比赛的老年平地赛马中，左心室射血分数和左心室质量的综合值与比赛评分呈正相关，解释了总体表现变化的25 - 35%，并且与障碍赛中较长距离比赛的表现也密切相关（23%）。这些数据提供了首个直接证据，表明心脏大小会影响一群哺乳动物跑步运动员的运动表现。
