Effects of inspiratory muscle training and postural challenge on cardiorespiratory coupling in amateur athletes

Cardiorespiratory coupling is defined as the link between respiration and heartbeat and has been previously studied with respect to the inspiratory onset. The repeatability of the latency of the R-wave with respect to the phase transitions of respiration was taken as an index of coupling and tested in two groups of amateur athletes during a rest-to-stand protocol carried out before and after inspiratory muscle training. Our results suggest that the orthostatic challenge causes a reduction of cardiorespiratory coupling strength especially after moderate inspiratory training and that both inspiratory and expiratory onsets should be considered in the assessment of cardiorespiratory coupling.