COORDINATION BETWEEN BREATHING AND FINGER TRACKING IN MAN

Arm and leg movements are known to produce temporal pattern changes of breathing. This can be interpreted as coordination, as defined by von Hoist (1939). The aim of the present study was to find whether breath ing exerts an influence in a reverse direction on a nonrespiratory mov ement as well. A pursuit tracking test was used, and test individuals (N = 19) were instructed to track a visually presented step function b y flexion or extension of their right index finger. Velocity and preci sion of the step responses proved to be dependent on their relation to the breathing time course; the differences between inspiratory and ex piratory responses were smaller than those within each half-cycle. The movements were performed more rapidly and more precisely in about the middle of each half-cycle than immediately after the respiratory phas e transition or during the second half of each inspiration or expirati on. Discontinuous short-lasting motor actions exerted a coordinative i nfluence on respiration comparable with that of periodical events: Bre aths coinciding with step responses were shortened, preferably when th e preset step was given early in the inspiration. It was hypothesized that the reciprocal effect between both motor actions changes periodic ally. In the first part of each respiratory half-cycle, the respirator y rhythm exerts only a weak influence on additional movements, but it can be altered easily by simultaneous motor processes. Toward the resp iratory phase-switching, the respiratory rhythm behaves more stably ag ainst coordinative influences and becomes capable of impairing an addi tional movement.