The effect of electroacupuncture with different frequencies on muscle oxygenation in humans

Abstract

The aim of the present study was to investigate the effect of electroacupuncture (EA) with different frequencies on muscle oxygenation in humans. The subjects were 8 healthy male volunteers. Muscle oxygenation was measured using near-infrared spectroscopy (NIRS). Blood pressure (BP) and heart rate (HR) were monitored simultaneously. After baseline recording, EA was given for 15 min and recovery was measured for 20 minutes. The procedure of EA at 1 Hz, at 20 Hz, and at control followed in the same subjects. Tissue oxygenation index (TOI) decreased during EA at 20 Hz (P < 0.05) and increased during the recovery period. Normalized tissue hemoglobin index (nTHI) also decreased during EA at 20 Hz and increased during the recovery period (P < 0.05), whereas TOI and nTHI in the EA at 1 Hz did not change significantly throughout the experiment. The peak TOI and nTHI values at 20 Hz during the recovery period were higher than the values at 1 Hz and in the control (P < 0.05). BP and HR remained constant. These data suggest that the supply of oxygen to muscle decreased during EA at 20 Hz and increased after EA at 20 Hz, without any changes in HR and BP.

Figure 1

Measurement site and electroacupuncture (EA) stimulation point.

Figure 2

Percent changes in tissue oxygenation index (TOI) during electroacupuncture (EA) stimulation. ^* P < 0.05 versus baseline values. ^#Significant difference from control and 1 Hz (P < 0.05). Values are mean ± SEM.

Figure 3

Serial changes in normalized tissue hemoglobin index (nTHI) values during electroacupuncture (EA) stimulation. ^* P < 0.05 versus baseline values. ^#Significant difference from control and 1 Hz (P < 0.05). Values are mean ± SEM.

Figure 4

(a) Peak tissue oxygenation index (TOI) and (b) normalized tissue hemoglobin index (nTHI) values during recovery period at control, 1 Hz, and 20 Hz. Peak TOI and nTHI values were significantly higher at 20 Hz, compared with those at the control and 1 Hz. ∗Significant difference from control or 1 Hz (P < 0.05). There was significant difference in peak TOI values between control and 1 Hz (P < 0.05). There was no difference in peak nTHI values between control and 1 Hz. Values are mean ± SEM.

Figure 5

Serial changes in (a) mean arterial pressure (MAP) and (b) heart rate (HR) at control, 1 Hz, and 20 Hz. MAP and HR were averaged every 2 minutes. Symbols represent 2-minute average values. There was no significant change in MAP and HR compared with baseline values. Values are mean ± SEM.