Fig. 2. Biochemical stress parameters. Data are mean ± standard errors. (A) The mean salivary cortisol in the stress and control groups. (B) The heart rate in the stress and control groups. *p< .05, ***p < .001.
For heart rate, a 2 × 6 mixed-measures ANOVA was conducted with one within-group factor Time (T1 to T6 time points) and one between-group factor Group (control group vs. stress group). The results revealed that the main effect of Time was significant, F (5, 305) = 15.86,p < .001, \(\eta_{p}^{2}\) = 0.21. The main effect of Group was also significant, F (1, 61) = 6.85, p = .011,\(\eta_{p}^{2}\) = 0.10. In addition, the interaction of Group × Time was significant, F (5, 305) = 15.95, p < .001,\(\eta_{p}^{2}\) = 0.21 (see Figure 2). Across the groups, simple effects analyses (Bonferroni corrected) revealed that the stressed participants showed significantly higher heart rates after completing the MIST session than the control participants at T3 (p< .001), T4 (p = .027), and T5 (p = .020).