Interactions of breathing with the postural regulation of the fingers

Objectives: The present study was pet-formed to detect the interactions bet ween breathing and the postural motor control of the fingers. A previous st udy revealed a scattering in the intraindividual motor responses which rese mbled a grouping. It is hypothesized to result from the influence of breath ing. Methods: Torque impulses and torque steps at two intensities were applied t o 17 healthy volunteers, to the II-IV fingers of their right hand. The subj ects had to compensate for these additional torque loads that were triggere d by a breathing-related signal and elicited at 4 different moments within a breath. Results: We demonstrated mutual influences between breathing and the regula tion of finger posture. The reaction to a torque load was faster at the beg inning of inspiration but more precise when the torque load was applied in mid-expiration. The motor response to torque loads was accompanied by chang es in the breathing time course, particularly when the torque load was elic ited during inspiration. The effects were most pronounced when torque steps were applied. The intensity of torque loads had no significant influence. Additionally, we observed that the respiratory phase-transitions often coin cided with the end of the applied torque steps. Conclusions: The results correspond well with the interactions existing bet ween breathing and single or rhythmical movements. Further investigations o f motor functions should consider this interdependence with breathing. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.