Chattanooga Wireless Professional - Summary

. ELECTROTHERAPY THEORY

EN
WIRELESS PROFESSIONAL
The chronaxy corresponds to the time value when 𝑄 = 0
i.e. 𝑄   + 𝑖𝑡 if 𝑄 = 0 therefore +𝑖𝑡 = 0 therefore 𝑖𝑡 =  and 𝑡  /𝑖
Fig. 4
12.1.2 Summary
Electrical stimulation, i.e. reducing resting potential to the stimulation threshold using an electric current, is
a phenomenon that fulfils a fundamental physiological law.
This shows us that:
1 The factor determining stimulation is the quantity of electrical
charges created by the current.
Stimulation must be considered in terms of the amount of current, which is the
product (𝐼𝑥𝑡) of the intensity (𝐼) times the duration of the pulse (𝑡).
2 This amount of current fulfils a fundamental formula:
𝑄   + 𝑖𝑡
where 𝑄 is a linear function of time.
Lapicque expresses this formula in another way by the “intensity - pulse duration”
ratio: 𝐼/𝑡+𝑖and he deduced that
a) the rheobase (𝑅ℎ): minimum intensity that must be reached in order to produce
stimulation using an infinite pulse duration
𝑅ℎ = 𝑖
b) the chronaxy (𝑡𝑐ℎ): minimum time in which a current with double the intensity of
that of the rheobase must be applied in order to produce stimulation
𝑡𝑐ℎ = /𝑖
We can note that the chronaxy can be calculated mathematically from Weiss’ fundamental formula as
shown in Figure 4.