Objective
To investigate the patterns of the temperature effect on motor nerve conduction parameters according to various warming methods and to obtain the most valuable method of warming in clinical setting.

Method
Twenty normal subjects were studied. After limb cooling in cold water, the cooled hands were warmed by hot pack, fan heater, and whirl pool. The median motor responses were recorded at abdnctor pollicis brevis after the stimulation at the wrist during warming at 1 min interval until the temperature increment reached plateau. We measured the temperature changes and conduction parameters were measured at each examination.

Results
The time constants for temperature increment and distal motor latency, duration, area of compound muscle action potentials showed shorter tendency by hot pack and whirl pool than by fan heater (p＜0.05). For the measurement of distal motor latency, time constant of whirl pool (2.49⁑1.21 min) was shorter than that of fan heater (7.12⁑3.12 min) or hot pack (5.96⁑1.98 min) (p＜0.05).

Conclusion
These findings suggest that the use of whirl pool is the most effective method for warming of the cooled limb.