[Study on adaptive changes of myocardial ultrastructure after endurance training at different intensities in rats]

The purpose of the investigation was to determine the adaptive changes of central mechanism of aerobic metabolism and to probe the best training intensity for developing the structure and function of heart most effectively. After endurance training at different intensities (including 26 m/min, 30 m/min, 36 m/min, 42 m/min) for 16 weeks, the rats were decapitated. Left ventricle were excised soon and were then processed for electron microscopy. Morphometry was performed at image analysis system. Quantitative analysis of ultrastructure of left ventricle and capillaries indicated that the best development of mitochondria inner membrane and cristea, the maximum improvement in number of capillaries, the most obvious enlarging of capillary cavity and the most remarkable shortening of maximum oxygen diffusion distance from capillary wall to the mitochondria appeared after training at the highest speed (42 m/min). It is demonstrated that after endurance training at different intensities the ultrastructure of all training groups showed good developments in varying degrees. Furthermore, endurance training at suitably high intensity could improve adaptation of myocardium most effectively.