FIGURE 8.

The dynamic changes (mean ± standard error) in (a) SDRR and (b) MMCA-derived RSA throughout the whole SDB exercises among the three modes, including mode 1 (red line, I: E = 1:1; breathing rate = 6 bpm), mode 2 (blue line, I: E = 1:2; breathing rate = 6 bpm) and mode 3 (green line, I: E = 1:2; breathing rate was guided as slowly as possible). Compared to the baseline stage (start-5min), parameters during the paced breathing stage (5-16 min) of all modes significantly increased, but in the recovery stage (about 16 min-end), only mode 3 showed significantly increased values. All indicators are calculated by a sliding window of 50 seconds with a 1-second step size.