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  Discussion on Heart size and performance
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DrO

Posted on Tuesday, Jul 12, 2005 - 11:43 am:

Since I own a stallion by the fastest TB ever to have lived, one who was reputed to have a tremendous heart size on necropsy, this caught my attention. It may be time to lay down the radiograph machine at the auctions and pick up the ultrasound:"

J Appl Physiol. 2005 May 26;

Left ventricular size and systolic function in thoroughbred racehorses and their relationships to race performance.

Young LE, Rogers K, Wood JL.

Centre for Equine Studies, Animal Health Trust, Newmarket, Suffolk, United Kingdom.

Cardiac morphology in human athletes is known to differ depending upon the sports-specific endurance component of their primary event, whilst anecdotes abound about superlative athletes with large hearts. As the heart is a key determinant of stroke volume and VO2max in mammals, we undertook a study to test the hypothesis that the morphology of the equine heart would also differ between trained equine athletes, depending upon their race type, and that left ventricular size would be greatest in horses racing successfully. Echocardiography was performed in 482 conditioned and race fit Thoroughbred racehorses engaged in either flat (race distance 1000-2500m) or jump racing (3200-6400m). Associations between different indices of left ventricular size and function and objective measures of race performance were determined using a standard regression approach. Body weight and gender adjusted measures of left ventricular size were largest in horses engaged in jump racing over fixed steeplechase fences compared to horses running shorter distances on the flat (range 8 - 16%). The observed differences in cardiac morphologies between horses suggest that subtle differences in training and competition also result in differing cardiac adaptations that are appropriate to the endurance component of the event. Derived left ventricular mass was strongly associated with published rating (quality) in horses racing over longer distances in jump races (p</=0.001),>1408 m), explaining 25-35% of overall variation in performance, as well as being closely associated with performance in longer races over jumps (23%). Predicted differences between otherwise equivalent horses with small and large hearts could thus explain a significant proportion of the difference between elite and non-elite racehorse performance, providing the first direct evidence that cardiac size influences athletic performance in a group of mammalian running athletes.

DrO
Member:
36541

Posted on Tuesday, Jul 12, 2005 - 2:45 pm:

NPR did an interview this am with a researcher who studied Lance Armstrong from 92 to 99. He said the first difference noted was the cyclist's heart size, as well as the extra-large great vessels. They tailored his training to stress the heart in particular ways, and documented the change with echo. A lot of this was prior to his cancer in 96, thus providing more evidence against doping. The researcher has a book coming out, but I don't think they are going to give up any training secrets. Dr. O, maybe this could give you a marketing edge - how would your guy look in a yellow jersey?!
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