Electrical stimulation is extensively used as the therapeutic and diagnostic tools at present. The effects of interferential current therapy(ICT) and transcutaneous electrical nerve stimulation(TENS) that are most commonly used in electrotherapy, have been evaluated by the subjective methods such as visual analog scale in human and by the electrophysiological methods such as nerve conduction studies in the experimental animal study, but their mechanism is not clear. And they had not been studied well regarding their electrophysiologic influences in human.

The objectives of this study are to find out whether the electrcial stimulation brings about the actual electrophysiologic change in human nervous system and to observe the differences in the effects between the two different types of electrical stimulation. According to the modes and sites of the applied electrical stimulation (conditioning stimulation), 42 healthy adult volunteers were divided into 4 groups and then the conditioning stimulation was applied for 15 minutes in each group. Four kinds of electrodiagnostic studies were performed before and after conditioning stimulation, and they were sensory and motor nerve conduction studies, H reflex, F response and smatosensory evoked potential(SEP) of tibial nerves.

The results were as follows;

1) After all kinds of conditioning stimulation, the latencies in H reflex and SEP(P1) were significantly delayed(P<0.05).

2) Except the 4th group which was stimulated by TENS at the popliteal area, the latencies of F waves were increased in all other groups(P<0.05).

3) There were no significant changes in all parameters of the peripheral nerve conduction study and the P1N1 amplitude of SEP.

4) Tibial nerve stimulation had more influenced to the change of H reflex latency than the paraspinal stimulation(P<0.05).

5) ICT had more influenced to the change of F wave latency than TENS(P<0.05).

6) ICT had more influenced the change of P1 latency in SEP than TENS significantly(P<0.05).

According to the above results, the conditioning electrical stimulation brought about the electrophysiologic changes in the spinal cord and/or the proximal roots near spinal cord but not in the peripheral nerve.