**3.2. The autonomic nervous system during MI of isometric thenar muscle activity at 50 and 100% MVC**

Firstly, about purpose, the ANS recording procedure, experimental protocol, and statistical analysis, please refer to our previous research [40].

## *3.2.1. Materials*

Then, this research aimed to investigate the ANS activity during MI of isometric thenar activ-

Nine healthy volunteers were participated in this research (7 males, 2 females; mean age = 25.3 ± 5.3 years). All participants provided informed consent before the study commenced. This research was approved by the Research Ethics Committee at Kansai University of Health Sciences. All recordings were conducted in accordance with the Declaration of Helsinki.

The ANS activity was recorded using a heart rhythm scanner PE (Biocom Technologies, USA). The pulse wave from the photoplethysmography sensor attached on earlobe was measured. The low frequency/high frequency (LF/HF) ratio was calculated by analyzing measured the pulse

For the rest trial (rest), the ANS activity was recorded during relaxation for 5 min. The European Society of Cardiology and the North American Society of Pacing and Electrophysiology recommend 5 min recordings for heart rate variability analysis [43]. Subsequently, for the motor task, participants learned the isometric thenar muscle activity at 50% MVC (i.e., participants press the sensor of pinch meter by left thumb and index finger at 50% MVC) for 1 min. They were instructed to keep the 50% MVC value (kgf) measured numerically on the display of pinch meter. For the MI trial, participants performed MI of isometric thenar muscle activity at 10% MVC for 5 min. The ANS activity was recorded during MI (10% MI) and immediately after 10% MI trial (post) for 5 min respectively. The above process was defined as the MI at 10% MVC condition (10% MI condition). The ANS activity recording under 50% MI condition was performed using the same protocol as 10% MI condition.

The normality of the ANS activity data was not confirmed by using the Kolmogorov-Smirnov and Shapiro-Wilk tests. We used a nonparametric method in this research. The LF/HF ratio among three trials (rest, MI, post) under two MI conditions (10% MI and 50% MI conditions)

We also calculated the relative value obtained by dividing the LF/HF ratio during MI under four MI conditions by that at rest. The relative values among two MI conditions were compared using the Wilcoxon signed rank test. We used SPSS statistics ver. 19 (IBM Corp., USA)

The LF/HF ratio during MI under two MI conditions was greater than that at rest (50% MI vs. Rest, \**p* < 0.05) (**Tables 9**, **10**). The LF/HF ratio immediately after MI under two MI conditions

for statistical analysis. The threshold for statistical significance was set to p = 0.05.

wave. The LF/HF ratio is considered to be an index of the sympathetic nerve activity.

ity at 10 and 50% MVC [40].

62 Evolving BCI Therapy - Engaging Brain State Dynamics

*3.1.4. Experimental protocol*

*3.1.5. Statistical analysis*

*3.1.6. Results*

was reduced to rest level (**Tables 9**, **10**).

*3.1.3. The ANS activity recording procedure*

These conditions were performed randomly on different days.

were compared using the Friedman test and Scheffe's post hoc test.

*3.1.2. Materials*

Ten healthy volunteers were participated in this research (8 males, 2 females; mean age = 25.3 ± 5.3 years). All participants provided informed consent before the study commenced. This research was approved by the Research Ethics Committee at Kansai University of Health Sciences. All recordings were conducted in accordance with the Declaration of Helsinki.
