On the Relationships between Minor Tremor and Ballistocardiogram in Man

The minor tremor (MT), or microvibration, of the thenar muscles was recorded over in normal adults under various physiological conditions. In addition to MT, the ballistocardiogram (BCG), electrocardiogram (EKG) and respiratory movements were also traced simultaneously to determine the correspondence between MT and the pulsation of the heart. In. the relaxed awake state, the dominant vibrations of MT were found out to appear in corresponding very well to I, J and K and L, M and N waves of BCG as well as R and T waves of EKG. These changes corresponding to BCG or EKG were, on the other hand, demonstrated to be potentiated and weakened by deepening and stopping breathing, respectively. In addition, both MT and BCG were shown to cause a marked increase in amplitude and frequency in cases of Master two step test as the load of EKG, in which facilitatory changes of circulatory and respiratory systems can be provoked. From the above-mentioned results, it seems likely that the facilitatory and inhibitory changes in the pulsation of the heart besides those in muscle tonus play an important role in the augmentation and inhibition in MT under various physiological conditions, and furthermore the respiratory changes in MT might be caused by respiratory changes of cardiac output in inspiratory and expiratory phases of respiration as well