Fig. 4

Associations between inspiratory and post-inspiratory loading and changes in diaphragm function assessed by neuromuscular coupling (NMC) over time. Curves represent fitted values computed by linear mixed models examining the interaction between time and exposure to the different loading conditions. Shaded regions represent 95% confidence intervals. The rate of change in diaphragm NMC did not significantly vary with the duration of exposure to elevated inspiratory effort (top left, p = 0.076 for interaction testing for differences in slope) or with the magnitude of estimated respiratory muscle effort (top right, p = 0.56 for interaction). The rate of decline in diaphragm neuromuscular coupling (NMC) was greater with more prolonged periods of post-inspiratory loading (bottom left panel, p = 0.007 for interaction) and with increasing magnitude of post-inspiratory loading (bottom right panel, p = 0.009 for interaction)