Variability of Electrocardiogram Elements in 6-7 Years Children Under the Influence of Physical Activity in the Conditions of the European North

The Aim: to determine the duration of the ECG intervals of PP, PT, PQ, QT and TP segment in two groups of children of both sexes aged 6-7 years in control and under the influence of an active orthostatic test (AOP n = 20) and test- Martine-Kushelevsky (PM n = 15). Methods. We studied the duration of ECG intervals in the II standard lead before and after the application of orthostatic test and test- Martine-Kushelevsky. Indices after statistical analysis were presented by M ± SD and cardiointervalogramm. Results. During orthostatic test the heart rate increased by 24 %, the duration of the PP interval was down by15 % ( from 0.71 ± 0.1 s in the control to 0.60 ± 0.1 s ) PT - by 4 % (from 0.47 ± 0.03 s to 0.45 ± 0.03 s), QT - by 9 % (from 0.34 ± 0.02 s to 0.31 ± 0.01 s), segment of the TP - from 0.24 ± 0.1 s to 0.15 ± 0.1 s (38 %), and the duration of the PQ interval increased insignificantly by 8% (from 0.13 ± 0.01 s to 0.14 ± 0.01 s). During test- Martine-Kushelevsky, the heart rate increased by 21 %, the remaining indices changed by 17 % (from 0.64 ± 0.1 s to 0.53 ± 0.04 s), 5 % (from 0.44 ± 0.03 s to 0.42 ± 0.03 s), 3 % (0.31 ± 0.01 s to 0.28 ± 0.004 s) and 50 % (from 0.20 ± 0.1 s to 0.10 ± 0.03 s) respectively. The PQ interval remained unchanged. Correlations between the heart rate before and after the samples rs = 0.67 (AOP) and rs = 0.36 (PM), between РР rs = 0.69 (AOP) and rs = 0.26 (PM), between РТ rs = 0.93 (AOP) and rs = 0.74 (PM), between РQ rs = 0.78 (AOP) and rs = 0.67 (PM), between QT rs = 0.83 (AOP) and rs = 0.65 (PM) and between TP rs = 0.56 (AOP) and rs = 0.37 (PM). Conclusions. As a result of the action of two functional tests on the cardiovascular system of children aged 6-7 years, the heart rate increased and the duration of the ECG intervals was shortened. The variability of the indicators was less than in the control. The most significantly changed the parameters of the TP segment.