Mean diaphragm force-frequency curves for sham-operated wild-type (WT) animals (controls, black), cecal ligation puncture (CLP)-operated WT animals (CLP, red), sham-operated calpastatin-overexpressing animals (CalpOX, green), and calpastatin-overexpressing CLP-operated animals (CalpOX + CLP, blue). CLP resulted in a large reduction in the force generated in response to all stimulation frequencies for WT animals (P < 0.05 for comparison of all forces for WT sham-operated with WT CLP-operated animals). In contrast, calpastatin-overexpressing animals were resistant to the effects of CLP, with the forces generated by the calpastatin-overexpressing CLP animals significantly higher than forces generated by the WT CLP animals (P < 0.05 for all stimulation frequencies). *Statistical significance.