Objectives: To evaluate the influence of physiological load on postural control in concert with a precise determination of fatigue level. The secondary goal was to determine the usefulness and a reliability of the postural control measurement device in clinical practice. Subjects and methods: Thirty subjects were randomly divided into two groups. We conducted multistage all-out exertion protocol of spiroergometric testing on cycle-ergometer until exhaustion with continuous measurement of ventilatory-metabolic and subjective parameters of fatigue level. Before the beginning of the exertion protocol the experimental group performed the three trial balance tests on SportKAT platform. Each step of the protocol lasted for three minutes and was followed with three minute breaks during which the subjects underwent the static and the dynamic balance testing. In a control group, the protocol encompassed only balance testing procedures followed by 3 minute rest periods. After the completion of the testing procedures, the intensity zones were determined for each testing stage in experimental group by means of the ventilatory-metabolic parameters. Results: The significant differences in both static and dynamic balance tests were found in experimental group. Post-hoc analyses revealed significant negative effect of fatigue on the static balance with three „balance thresholds“: at the first rest/work transition, after the anaerobic threshold and at maximal exertion level. The dynamic balance was negatively affected with fatigue, however no „balance thresholds“ were distinguished. No significant changes in neither static nor dynamic balance abilities were observed in the control group. The moderate correlation between the static and the dynamic balance abilities was found. No statistically significant learning effect of 6 repetitions on Balance Indices was observed. Conclusion: The physiological load negatively influences the balance abilities and for static postural control it can be observed through three „balance thresholds“. The six repetitions of the balance tests do not reveal the learning effect on the test results.