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the minimum time at which an electric current must flow at a voltage twice the rheobase to cause a muscle to contract. In a strength-duration curve for muscle stimulation, it is the pulse width at a voltage twice that at the rheobase.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


A measurement of excitability of nervous or muscular tissue; the shortest duration of an effective electrical stimulus having a strength equal to twice the minimum strength required for excitation.
[G. chronos, time, + axia, value]
Farlex Partner Medical Dictionary © Farlex 2012
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References in periodicals archive ?
Two parameters related to excitability were measured: rheobase and chronaxy. The rheobase of the DB8 and DB12 groups had a significant increase of 7.9% and 14.4%, respectively, compared to rheobase that was observed in the respective E groups (3.4 [+ or -] 0.09 V and 3.45 [+ or -] 0.09 V vs 3.01 [+ or -]0.09 V and 3.15 [+ or -]0.06 V, respectively).
In the STZ-induced diabetes model used herein, both chronaxy and rheobase were increased in the SN.
The electrophysiological parameters PPA, conduction velocity of CAP first and second components, rheobase, and chronaxy were analyzed after nerve stabilization and the control values were 7.1 [+ or -] 0.27 mV, 85.4 [+ or -] 2.34 m/s, 30.8 [+ or -] 1.11 m/s, 3.4 [+ or -] 0.22 V, and 51.5 [+ or -] 2.34 ms (n=87), respectively.