After-effects of slow-paced breathing on the Bereitschaftspotential preceding voluntary movement

The concurrent effects of volitional breathing on motor-related brain regions have been documented in several studies, but it remains uncertain whether its after-effects influence neural processes involved in motor preparation. This study investigated whether a brief slow-paced breathing intervention alters the dynamics of the Bereitschaftspotential (BP) preceding voluntary movement. Thirty healthy participants were randomly assigned to a slow-paced breathing (SB) group (n = 15), who performed 5 min of 0.1-Hz breathing, or to a resting breathing (RB) group (n = 15). Before and after the intervention, participants executed self-paced isometric right index finger abductions while electroencephalography, electromyography, force output, end-tidal carbon dioxide (ETCO₂), and alertness were recorded. ETCO₂ was also monitored during the intervention. BP amplitudes were quantified for the early component associated with the supplementary motor area (Cz and Fz; - 800 to - 500 ms) and the late component associated with the primary motor cortex (C3; - 300 to 0 ms). Mixed-design ANOVAs revealed significant Group × Phase interactions for both early and late BP components (p < 0.01), with increased negativity after the intervention only in the SB group. Normalized electromyographic activity and force output remained unchanged, and subjective alertness showed a small overall decline that did not differ between groups. Within the SB group, lower absolute ETCO₂ levels during the intervention were associated with a more negative early BP amplitude after the intervention (ρ = 0.521, p = 0.049), whereas no correlation was found for the late BP. These findings suggest that a short session of SB enhances preparatory cortical activity, reflected in increased early and late BP components. Early BP enhancement was linked to lower ETCO₂ levels during the breathing task, indicating modulation of supplementary motor area excitability. SB may offer a simple, noninvasive means to alter cortical preparatory states.