The Strength-Duration Curve

The strength-duration curve is a plot of the lowest (threshold) current (I) required for stimulation versus pulse duration (d); it forms the basis for describing the excitability of a given tissue. It is extremely useful in all manner of studies in which excitable tissues are stimulated because it describes the manner in which the current required is changed when the pulse duration is changed. Moreover, it can be used to determine the charge and energy-duration relationships. It will be the objective of this communication to show how the essential constants can be obtained.