Pesq. Vet. Bras. 32(Supl. Electrocardiography can be used to quantify the training and athletic performance as well as evaluating the cardiac function under the effect of exercise identifying the influence of cardiac anomalies, and deleterious effects of stress ahead of heart function. Considering the complexity of the physical efforts inherent in polo ponies in competitions, together with the lack of reports in the literature, on the demand resulting for heart. The aim of this study was to identify and evaluate the cardiac effects of electrocardiographic exercise in polo horses in order to support data for understanding the physiological cardiac demand of this sport. We evaluated 27 equine practitioner polo at rest and between five and ten minutes after exercise. The results showed that the observed changes in the duration and P wave amplitude and duration of PR and QT interval were considered in physiological response to increased heart rate. The diphasic P wave found at rest and when atrial hypertrophy represented bifida represented different points of activation of the sinoatrial node. As expected, the QRS complex has not undergone major changes. The ST-segment elevation and T wave changes observed after exercise could pose adverse effects to the myocardium, but studies examining multiple factors are needed to confirm this association and define your actual question. The increase in QTc suggested fatigue mild myocardial represented high heart demand for this type of exercise. The heart score showed that these animals were within the pattern of cardiac adaptation to a horse athlete. The rapid recovery of HR showed good conditioning of these animals. The pacemaker migration was observed in most animals proven to be a normal finding horse athlete. We observed a low incidence of changes in cardiac rhythm.INDEX TERMS: Cardiac function, electrocardiographic index, physiology exercise.

RESUMO.-Considerando a complexidade do esforço ϐísico inerente a cavalos em competições de polo e da carência de relatos na literatura sobre os efeitos cardíacos resultantes de um chukker, associado ainda a dinâmica do peso, o objetivo deste estudo foi de avaliar por meio da ecocardiograϐia, 27 equinos atletas de polo, submetidos à partida treino, em repouso e após o exercício. Os resultados demonstraram que esta modalidade alterou diversos índices ecocardiográϐico no período de cinco a dez minutos do término de um chukker. Foram eles, estruturais com: redução da espessura do septo interventricular e parede livre do ventrículo esquerdo e aumento do diâmetro interno do ventrí-culo esquerdo em sístole, e funcionais como: aumento do débito cardíaco e frequência cardíaca, enquanto que o volume sistólico, a fração de encurtamento e a fração de ejeção reduziram. A perda de peso corporal não foi signiϐicativa, Considering the complexity of the physical effort inherent in polo horses in competitions and the lack of reports about the cardiovascular effects resulting from a Chukker, yet the dynamics of the associated weight, the aim of this study was to evaluate by echocardiography with 27 horses polo athletes who underwent training starting at rest and after exercise. The results showed that this method has changed several echocardiographic indexes within ϐive to ten minutes before the end of a Chukker. It was they, as structural index, thickness reduction interventricular septum and left ventricular free wall and increased left ventricular diameter, and functional as an increase in cardiac output and heart rate, while stroke volume, fractional shortening and ejection fraction reduced. The weight loss was not signiϐicant, so was not associated with echocardiographic changes. These results suggest that cardiac demand was high, indicating the importance of the physical and cardiovascular training speciϐic to this modality. INTRODUÇÃOO conhecimento das exigências competitivas de diferentes esportes é importante para a concepção de programas de treinamento adequados. Assim, pode-se garantir que os animais alcancem um nível suϐiciente de condicionamento, reduzindo o risco de esforço excessivo e lesão, conseguindo melhora no desempenho em relação ao potencial genético individual. No que diz respeito à complexidade do desaϐio ϐísico que cavalos de polo são submetidos, há poucas publicações sobre as demandas ϐisiológicas dos animais em relação a essa modalidade. Sendo que, em contrariedade a maioria dos esportes equestres, a demanda ϐisiológica de um jogo de polo é variável, pois se intercalam momentos de pausa, mudanças de velocidade e direção de movimentos,

Front of exercise, the organic systems may suffer water-electrolyte and acid-base imbalances, particularly in the case of blood gases, demonstrating variations from different causes, whether respiratory and/or metabolic. Understanding the physiological adaptations to exercise is essential in the search for the optimum performance. In this way, this study measured the venous blood gases (pO 2, pCO 2 ), as well as the oxygen saturation (SatO 2 ) in healthy equines, Arabian horses finalists in 90km endurance races. A total of fourteen Arabian horses were evaluated, nine males and five females, between six and 12 years old, finalists in 90km endurance races. There was a significant reduction in pO 2 , pCO 2 and SatO 2 after the exercise, however, the values remained within the normality range, and did not change the athletic performance of the animals, indicating a temporary alteration, assuming thus a character of physiological response to the exercise performed. The equines, finalists in 90 Km endurance races, demonstrated efficient ventilatory process, without any alterations in the athletic performance, being adapted to the type of exercise imposed.INDEX TERMS: Arabian horse, blood gas, endurance.¹