*3.1.3. The ANS activity recording procedure*

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

The relative values of the LF/HF ratio did not exhibit significant differences between two MI

**Rest 10% MI post**

The Application of Motor Imagery to Neurorehabilitation

http://dx.doi.org/10.5772/intechopen.75411

63

**Rest 50% MI post**

LF/HF ratio (%) 1.23 ± 0.75 2.73 ± 3.68 1.54 ± 0.52

LF/HF ratio (%) 1.74 ± 1.16 2.92 ± 2.17\* 2.07 ± 1.42

Firstly, about purpose, the ANS recording procedure, experimental protocol, and statistical

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.

The LF/HF ratio during MI under two MI conditions was significantly greater than that at rest (50% MI vs. Rest, 100% MI vs. Rest, \**p* < 0.05) (**Tables 12**, **13**). The LF/HF ratio immediately

The relative values of the LF/HF ratio did not exhibit significant differences between two MI

Our previous works demonstrated significant increase of the LF/HF ratio during MI at various imagined muscle contraction strengths (i.e., 10% MVC, 50% MVC, and 100% MVC) [40, 44]. Thus, MI of isometric thenar muscle activity can increase the sympathetic nerve activity as with previous researches [42]. The central command is defined as a feed-forward mechanism by which activation of cardiovascular and respiratory centers is accomplished by descending signals from central nervous system [45]. TMS delivered over the primary motor cortex

after MI under two MI conditions was reduced to rest level (**Tables 12**, **13**).

**3.2. The autonomic nervous system during MI of isometric thenar muscle activity at** 

conditions (**Table 11**).

\*

**50 and 100% MVC**

*3.2.1. Materials*

*3.2.2. Results*

conditions (**Table 14**).

**3.3. Discussion**

analysis, please refer to our previous research [40].

**Table 9.** Changes in ANS activity under 10% MI condition.

*p* < 0.05; significant difference between rest and 50% MI trial.

**Table 10.** Changes in ANS activity under 50% MI condition.
