The aim of the investigation was to assess the parameters of urgent adaptation of the heart and peripheral vasculature to single physical exercises to determine an individually safe value of motor activity.Materials and Methods. The experiments were carried out on 84 mongrel male dogs. Physical exercises were modeled in laboratory environment by treadmill run. Three types of exercises were used in the experiment: mild, optimal and excessive. Exercise duration was controlled individually, for each animal considering cardio-respiratory system state by heart rate. Cardiac work was assessed by echocardiography and electrocardiography, peripheral circulation -by hindleg rheovasogram.Results. Experimental findings indicate significant alterations in cardiac conducting system under single physical exercises. A single mild exercise causes the increase of minute blood output due to heart rate increase. Hind leg muscular blood filling decreases. An optimal exercise results in minute blood output increase due to stroke blood volume growth. Myocardial contractility increases. Muscular blood filling rises. In excessive load increased stroke output is accompanied by left ventricular cavity dilatation. Pulse volume decreases, peripheral vasculature elasticity reduces, and hind leg muscular venous outflow gets worse.Conclusion. urgent adaptation of the heart and peripheral vasculature in single physical exercises shows as a marked response to a simulated factor. The technique to assess the body adaptation considering cardiovascular system condition enables to calculate individual volume of physical activity and develop recommendations for it to be used efficiently in medicine.
The aim of the investigation was to reveal the spatial organization types of sinoatrial nodes in animals with different levels of body functional reserve after a single maximal exercise.Materials and Methods. The research was carried out on 24 male mongrel dogs. Treadmill run under laboratory conditions was used to model a single maximal exercise. The exercise time was individual for each animal due to its cardio-respiratory system. A body functional reserve level was determined by the running time to refusal and the heart rate (HR) during the exercise. We studied the sinoauricular area structure using light and transmission electron microscopy. Tissue organization of myocardium was analyzed using the methods of stereology.Results. According to HR dynamics, we distinguished two main types of functional response to maximal (excessive) exercise: type I, high HR during the running, and type II, low HR. The response types on exercise also differed in the running time and resting HR (p<0.05).Based on stereological test findings we described the peculiarities of spatial organization of conductive and contractile myocardium in animals with different functional responses characterized by various ratios of the main tissue components. Stereological parameters in type I animals were similar to those in intact animals of a control group. Conductive and contractile myocardium in type II animals significantly differed in a relative volume of cardiomyocytes and connective tissue components from those in controls and type I animals.Conclusion. The results of morphological studies of sinoauricular region in animals with different levels of functional body reserve compared to physiological parameters enable to predict the structural changes in the sinoatrial node area after an excess motor load.
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