The stock market indexes in research on human balance

Purpose: The aim of the study was to demonstrate the possibility of using stock exchange indices to assess the ability to maintain balance as a supplement to analyzes using values determined in the time and frequency domains. Methods: 83 healthy people (56 fe-males, 27 males, age years 21 SD = 1.3 years) participated in the research. Measurements were performed with open and closed eyes and in the virtual environment with two sceneries oscillating at four frequencies. The results determined in the time and frequency domains were analyzed in relation to the results calculated with the use of stock exchange indicators for which the Trend Change Index was for-mulated. Performed measurements made it possible to determine the average COP speed, the average COP speed and range of movement towards AP, power spectral density PSD and stock exchange indices. Results: In the case of PSD values for the ranges above and below 0.5 Hz, statistically significant differences occurred for most measurements. Obtained values of TCI coefficient were similar and no statistically significant differences were observed. The maximum values of the PSD medians were obtained in trials with the oscillating scenery. Conclusions: Conducted analyzes showed that use of stock exchange indicators broadens the interpretative possibilities of COP measurements by determining the number of consecutive skips (changes in the direction) of the COP and prioritizing according to the times between them. The applied stock market analysis methods also filtered out changes in the position resulting from noises that could not be removed with the use of standard low-pass filters.