Introduction Individuals with X-linked myotubular myopathy (XLMTM) and other centronuclear myopathies (CNMs) frequently have profound respiratory insufficiency that requires support early in life. Still, few quantitative data exist to characterize respiratory motor function in CNM. Methods We evaluated the reliance upon mechanical ventilation (MV), ventilatory kinematics, unassisted tidal volumes, and maximal respiratory pressures in 14 individuals with CNMs, including 10 boys with XLMTM. Results Thirteen participants required full-time, invasive MV. Maximal inspiratory pressures were higher in subjects who breathed unsupported at least 1 hour per day than 24-hour MV users [33.7 (11.9–42.3) vs 8.4 (6.0–10.9) cm H2O, P<0.05]. Years of MV dependence significantly correlated with MEP (r=−0.715, P<0.01). Discussion Respiratory function in CNMs may be related to deconditioning from prolonged MV and/or differences in residual respiratory muscle strength. Results from this study may assist in evaluating severe respiratory insufficiency in neuromuscular clinical care and research.