The Tohoku Journal of Experimental Medicine
Online ISSN : 1349-3329
Print ISSN : 0040-8727
ISSN-L : 0040-8727
Application of the Sinusoidal Alternating Current at Frequency of 3 cps. for Measuring Fatigue
Tosisada MitaMakoto SatoSadao YaegashiAkira AkihamaTeiichi Yoshino
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1959 Volume 69 Issue 2-3 Pages 123-130


Using the sinusoidal alternating current (A. C.) at 3 cps. in frequency as the stimuli of the eye, we determined the threshold (S1) for appearance of the flickering phosphene, and the threshold (S2) for disappearance of it. Calculating the difference of both thresholds, namely S1-S2=ΔS, we investigated the applicability of this measure (ΔS) as an index for measuring fatigue. At the same time, Motokawa's ΔS for 20 cps., C. F. F. and the body impedance were measured for comparison with our measure (ΔS for 3 cps.).
1. Each value of S1, S2 and ΔS for 3 cps. was the smallest in darkness, while that for 20 cps. was the smallest under moderate illumination.
2. In the course of 10 hour's duty, the values of ΔS showed two maxima before and after lunch respectively. This finding is consistent with the result reported by Abe & Byonshik. Impedance did not show so remarkable a variation in the same course as the former.
3. When the work of 500-2800 kg-m was performed by the 15 healthy subjects, the temporal variations in the values of ΔS, impedance and C. F. F. were investigated. The value of ΔS increased with increase in the amount of work, while the values of C. F. F. and the body impedance decreased with increase in load. These findings are in conformity with the results studied by Motokawa's original method.
4. From the results mentioned above, it was concluded that the A. C. at 3 cps. can be useful for measuring fatigue as did the A. C. at 20 cps. by Motokawa et al. And the merits and demerits of our method on the practical application were discussed in comparison with Motokawa's method.

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