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

Cardiointervalography (CIG) was performed sequentially (5 min each) under conditions of clinostasis and orthostasis for the purpose of indirectly proving the synthesis of non-neuronal acetylcholine (NN-AC) under the influence of endurance training in eight elite ski racers (master of sports (MS), master of sports of international class (MSIC)) of national team of the Republic of Tatarstan in the preparatory and competitive periods, as well as K.D. (MS, first author of the article), member of this team, during all three periods of the annual cycle including transition period. The values of 15 indicators of heart rate variability (HRV) were investigated, 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, MxDMn and SI, or stress index) indicators. It was found that the medians of most HRV indicators during the active transition from clinostasis to orthostasis are changing, but the degree of change depends on the preparation period (the exception is the median RMSSD, which decreases by the same amount during the transition to orthostasis throughout all three periods). In particular, changes in the medians of HF, LF, HF%, LF%, LF/HF, RRNN, HR, and pNN50% were minimal in the 1st (preparatory) period and maximum in the 3rd (transitional) period. This could be explained by the “restraining” effect of NN-AC the synthesis of which in the preparatory period is probably higher than in the transition period. When implementing an orthostatic test, the marker of the presence of NN-AC synthesis in the myocardium is the median TP and its dynamics; in this case TP has high values of the median in clinostasis and their decrease in orthostasis, and in the absence of NN-AC synthesis, low values of the median TP in clinostasis and their growth in orthostasis. The degree of change in medians of pNN50%, SDNN, MxDMn, and absolute power of VLF waves is also the NN-AC synthesis marker.