<b>Abstract</b>— <p>The purpose of this work was to determine the effect of the level of nitric oxide in the blood on the function of external respiration and blood pressure in professional cross-country skiers during the performance of the test “until exhaustion.” The observation group included professional cross-country skiers (<i>n</i> = 59) who were current members of the national team of the Komi Republic (62° N) with normotensive (<i>n</i> = 27, group H) and hypertensive (<i>n</i> = 32, group G) reactions to the bicycle ergometric test “until exhaustion.” At rest, while at their anaerobic threshold level, during peak load, and during the recovery period (5th min) were determined the level of stable nitric oxide metabolites and cardiorespiratory parameters. In group H cross-country skiers, during the “until exhaustion” test and at the 5th minute of the recovery period, NO₃ is primarily involved in regulating the function of external respiration and arterial pressure. The development of hypertensive reactions to exercise in group G athletes and their lower physical performance are due to NO₃ deficiency. It has been shown for the first time that under the influence of physical exercise, the respiratory system in group H is more strained, while in group G, the cardiovascular system is more strained.</p>