Test in apnea your 0.2 Hertz frequency peaks.

by Pierre-Marie GAGEY & Alain SCHEIBEL

Institut de Posturologie, Paris


If, on the frequential analysis of a patient's stabilogram, you find a frequency peak at 0.2 Hertz and if you do not believe there is any link between that peak and the ventilatory rhythm, you just have to do immediately another recording in the same conditions but in apnea and you will then be convinced by images such as the following (figure 1 & 2).

FIG. 1 - Recording under normal ventilatory rhythm.


(Recording at the Institut de Posturologie by Alain SCHEIBEL)


FIG. 2 - Recording in apnea



(Recording at the Institut de Posturologie by Alain SCHEIBEL)



Since several years, TARDY and I think that the frequency peaks at 0.2 Hertz are related to a disappearing of the "Respiratic" synergy that normally cancels the effects of the ventilation movements on the movements of the subject's center of gravity (see "the Posture and Ventilation mystery" or "Norms of the frequential analyses" or again "Is there an infracanalicular pathology" on this Web site).

However, some do not believe that this postural sway is related to ventilation - they seem to think that the body mass can be mobilized by movements that have the rhythm of ventilation, but without being induced by ventilation. Because we know that the postural sway recorded at 0.2 Hertz is related with the movements of the center of gravity much more than with the movements of the center of pressure, as shown by Gurfinkel 25 years ago [1].

Reference :

1. Gurfinkel V.S. (1973) Physical foudations of stabilography. Agressologie, 14, C: 9-14.