Abstract
The article summarizes the results of the influence of 10 day stay and training in high altitude (1850 m ASL) on sport performance changes of cross country skiers at the level of aerobic, anaerobic and critical intensity load measured by heart rate (HR) and lactate concentrations in capillary blood. For verification was used a non-standardized running field tests (3 x 2km, with 10 minute rest). 7 subjects (deliberate sample, cross country skiers) performed the test five times altogether: initially in lowlands (480 m ASL), three times in high altitude (3rd, 6th and 9th day of stay) and the last 10 days after return to lowlands.
HR and lactate levels at aerobic and anaerobic thresholds were higher in high altitude compared to lowlands during all tests, however, they did not change at critical intensity in either the places. Average values of HR and lactate levels achieved during the lowland test 10 days after returning from high altitude were significantly lower at all three intensities in comparison with initial data.
The sport performance at aerobic and anaerobic thresholds during 10 day stay and training of cross country skiers in high altitude decreases, however significantly improves (in comparison with initial data) after the return to lowlands.