Cardiointervalogram Indicators in Conditions of Clinostasis and Orthostasis in Elite Ski Racers in the Course of the Annual Macrocycle

In order to indirectly prove the presence of neuronal acetylcholine (NN-Ach) synthesis in the ventricles of the heart, which occurs under the influence of endurance training, in 8 elite ski racers (MS, MSMC) of the national team of the Republic of Tatarstan in the preparatory and competitive periods, as well as in a member of this team, athlete K.D. (MS, the first author of the article) in all three periods of the annual cycle, including during the transition period cardiointervalography (CIG) was performed sequentially (for 5 min) in the conditions of clinostasis and orthostasis. The values of 15 indicators of heart rate variability (HRV) were studied, in particular 8 spectral (power of TP waves, absolute and relative power of HF-, VLF-, LF- waves, LF/HF ratio) and 7 temporal (RRNN, HR, pNN50%, RMSSD, SDNN, MхDMn and SI, or stress index) of indicators. It was found that the medians of most HRV indicators change during the active transition from clinostasis to orthostasis, but the degree of change depends on the preparation period (the exception is the median RMSSD, which decreases during the transition to orthostasis throughout all three periods by the same amount). In particular, the changes of the medians of HF, LF, HF%, LF%, LF/HF, RRNN, HR, pNN50% were minimal in the 1-st (preparatory) and maximal in the 3rd (transition) period. This can be explained by the «restraining effect of NN ACh, the synthesis of which in the preparatory period is probably higher than in the transitional period. When implementing an orthostatic test, the median of TP and its dynamics are a marker of the presence of NN-Ach synthesis in the myocardium - in this case, TP is characterized by high median values in clinostasis and their decrease in orthostasis, and in the absence of NN-Ach synthesis, low median TP values in clinostasis and their growth in orthostasis. A marker of NN-Ach synthesis is also the degree of change in the medians of pNN50%, SDNN, SDNN and the absolute power of VLF-waves.