Hair cortisol
The scores obtained for the hair cortisol were significantly different from the normal distribution in case of the scores for HIIT group in the Time 1 assessment (The changes in the hair cortisol levels and psychological variables before and after 8-week intervention in the HIIT (HIIT group consisted of 22 women; EDU group consisted of 16 women. Bold type indicates significant difference in the outcome variable. We used Wilcoxon’s test to verify the within group differences in the cortisol levels in the HIIT group and Student’s t test for dependent variables in the EDU group. We found significant differences between Time 1 and Time 2 assessments both in the HIIT group (Since both groups differed significantly in the first assessment, we decided to add additional information about the relationship between the initial scores for hair cortisol and the magnitude of change in both groups. To do so we decided to correlate the values obtained in the first assessment and the values of the difference between the two assessments (Worth to mention is also the fact that in the HIIT group the increase in hair cortisol was observed among 72.73% of participants, and in the EDU group among 18.75%. The difference between these two groups was statistically significant (The Intention-to-treat analysis was conducted on the scores coming from all 66 participants with the use of linear interpolation. The analysis revealed similar results as the above-described analysis: that both groups differed significantly in both—Time 1 and Time 2 assessments. However, although in the EDU group we found significant difference between the two assessments, no change in this aspect was found in the HIIT group (The changes in the hair cortisol levels before and after 8-week intervention in the HIIT and EDU groups.