Level of habitual physical activity and parameters of the cardio-respiratory system in students
Objective: to analyze the parameters of the cardio-respiratory system in healthy students with different levels of habitual physical activity. Materials and methods: 106 students of Tula State University (61W, 45M, mean age - 22.9±0.4 years (M±m), mean body mass index 22.5±0.4 kg/m<sup>2</sup>) were included in the study. The observation time was one year. Colour Doppler Imaging echocardiography and respiratory function tests were provided. Duration of a breath-hold after deep inspiration and after exhalation was obtained. Self-reported questionnaire to examine level of habitual physical activity was completed in the same time. Results: 42% of students had low habitual physical activity, 32% visited fitness centers, swimming pools or participated in recreational sports games (medium habitual physical activity) and 26% engaged in sports not less than 8 hours per week (high habitual physical activity). The optimal LV relaxation existed in the group with medium habitual physical activity (mitral E/A ratio 1,76±0,08 versus 1,53±0,06 in the group with low and 1,70±0,07 06 in the group with high habitual physical activity). The rarest valve regurgitation and the lowest systolic pressure were obtained in the group with medium habitual physical activity. The diameter of the pulmonary artery positively correlated with level of habitual physical activity. The main parameters of respiratory function test increased due to the level of habitual physical activity. Exceeding of the normative indicators of respiratory test was noted only in the group with high physical activity. Results of duration of a breath-hold after deep inspiration and after exhalation closely correlated with echocardiography and respiratory test. Conclusions: adaptive changes due to physical activity increase the functional abilities of the cardio-respiratory system in healthy students. Optimal echocardiography parameters were found in the group with moderate physical activity. Breast Holding Test showed a connection with intracardiac hemodynamics and respiratory function and may be widely used for screening examinations.