Effect of precision aiming on respiration and the postural-respiratory synergy.

Precision manual tasks require a stable postural background which might be facilitated by respiratory modulations. We investigated the influence of performing a manual precision aiming task on respiratory rate and dynamics, and the coherence between respiration and center of pressure (COP) fluctuations (i.e., the postural-respiratory synergy). Participants aimed a pointer at targets of different sizes while seated or standing. Respiratory rate increased during the aiming period compared to a pre-task phase, but did not vary as a function of aiming difficulty. Recurrence quantification analysis revealed an increased incidence of slowly changing periods of chest movements during the most difficult aiming condition, which required the highest level of manual precision. Aiming, irrespective of difficulty, led to increases in the regularity of the respiratory pattern. Increases in respiratory rate during aiming were accompanied by an increased level of coherence for the seated but not the standing posture, suggesting that task demands affect the organization of coordination across the postural-respiratory synergy. Functional demands of the task likely shape the effectiveness of compensation for respiration during precision aiming.