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Objective: to study the variability of the heart rate of athletes during hypoventilation training, which provides an increase in the result of speed-strength load.Materials and methods: Athletes performed speed-strength load with their hands on a training apparatus against the background of maximum voluntary breath holding before and after hypoventilation training. The duration of breath holding, the number of power movements, parameters of heart rate variability and electromyography were measured.Results: After hypoventilation training of athletes at rest, parasympathetic influences on the heart rate increased, which led to an increase in the total power of the heart rate spectrum from 3201 ± 520 to 4047 ± 585 ms2, the power of the low frequency of the heart rate spectrum from 1458 ± 216 to 2055 ± 392 ms2 and the standard deviation of the duration of adjacent cardiac cycles from 45 ± 5 to 52 ± 4 ms. Sympathetic influences increased during exercise against the background of maximum voluntary breath holding. The longer maximum voluntary breath holding was, the more power movements the athletes performed.Conclusion: Hypoventilation training changed the vagosympathetic balance of the athletes’ body, increasing their performance and hypoxic resistance.

According to some literature data, during voluntary long-term breath holding (BH), the heart rate (HR) increases, and according to others, it decreases.Objective: to determine the psychophysiological parameters that cause a change in HR during BH in athletes with different resistance to respiratory hypoxia.Materials and methods: HR at BH was studied in 14 beginner athletes, 15 basketball players and 12 swimmers-divers. Duration of BH was recorded. The HR was recorded on a heart rate monitor. After recording an electrocardiogram, the standard deviation of the duration of cardiac cycles was calculated. The arterial oxygen saturation was measured with a pulse oximeter. The statistically significant values of the correlation coefficient (r) were ≥0.33 with p < 0.05.Results: it was found that out of 41 sportsmen, HR increased by more than 5 % in 4, changed insignificantly in 7 and decreased by less than 5 % in 30. Beginner athletes had tachycardia, and BH was quickly interrupted by an imperative inhalation. The saturation of arterial blood with oxygen did not change and did not affect the change in HR. The decrease in heart rate in swimmers-divers in comparison with the other two groups of people examined was statistically significant (p < 0.05). The duration of BH had a direct correlation (r = 0.5) with bradycardia in these people. The duration of BH caused (r = 0.8) hypoxia, the value of which also directly influenced (r = 0.38) the severity of bradycardia. In addition, the decrease in HR depended on high HR (r = 0.36) and low HR variability (r = 0.38) before BH.Conclusion: tachycardia occurs in beginner athletes who experience discomfort with BH. Bradycardia occurs in sportsmen with a long-term BH setting without discomfort. Sympathicotonia in the prelaunch state predetermines the severity of bradycardia in BH. The duration of BH and the resulting hypoxia provide the occurrence of bradycardia.