Tourniquet obliteration of exercise-induced sensory nerve conduction augmentation.

OBJECTIVE: We previously discovered that minimally suprathreshold sensory nerve action potential amplitudes increased during isometric muscle contraction. In this study, the hypothesis was that the exercise-induced response could be blocked with a tourniquet. METHODS: A total of 21 healthy male and female subjects were recruited from the medical center. Baseline and postevent serial sural nerve recordings were made in the leg of 16 healthy subjects under the following conditions: (1) blood pressure cuff inflation at the arm, (2) isometric muscle contraction in the hand, and (3) conditions 1 and 2 combined. RESULTS: Results showed there was a 2.9 microV increase in the sural nerve response 5 min after muscle contraction compared to baseline at rest. The exercise-induced sensory response was largely obliterated by the blood pressure cuff with exception of the 1-min postexercise recording. CONCLUSION: In conclusion, the results show a tourniquet placed on the proximal arm blocks the effect of the muscle contraction of the hand on the minimally suprathreshold sensory sural nerve conduction recording in the ankle. The likely reason for this is the interruption of a thus far unidentified circulating factor. The clinical implication is the discovery of a sensory regulatory mechanism controlled by the motor system.