highly significantp < 0.01
There were highly significant differences (p < 0.01, one-way ANOVA) of MI between before and after stimulation in descending direction at NTB = 200, 250, 300 cyc, while lower significant differences (p < 0.05) of MI between before and after stimulation in ascending direction at NTB = 150 cyc, and no significant difference (p > 0.05) between them when NTB = 100 cyc.