Arndt-Schulz Curve

Laser Theory

The Arndt-Schultz Law  states that for a weak stimuli physiologic activity increases, a moderate stimuli inhibits activity, whilst a very strong stimuli abolishes activity.

Put another way, a small stimulus might not have a biological effect, a moderate stimulus may have a biostimulatory effect, whereas a large stimulus may have an bioinhibitory effect.

In the context of Low Level Laser Therapy the increasing stimulus may be in the form of Pain is reirradiation time or it may be increase in irradiance (beam intensity) .

Research studies have shown that dosages between 8.0 to 16.0 Joules/cm are necessary for pain reduction (a moderate stimuli inhibit) however tissue repair requires a dosage per treatment within the optimal therapeutic window between 0.5 and 5 Joules/cm2 (small stimuli stimulate)

Arndy Sculz curve for laser therapy dosages
Arndt-Schulz curve showing impact of laser therapy dose