From the authors:

From the authors:

In response to the question raised by N.G. Koulouris, we confirm that vital capacity (VC) and the respiratory muscle strength were all performed in the seated posture. We agree with N.G. Koulouris that correlations between the supine Borg and the supine respiratory muscle strength values might be better and it would be relevant to verify this hypothesis. However, as a matter of routine, only the VC was performed in both the seated and supine positions.

Measurement of the maximal inspiratory pressure (P_I,max) is conventionally easier to obtain from residual volume (RV) and greater inspiratory pressures are obtained at lower lung volumes. However, in the neuromuscular disorders, the recoil pressure of the respiratory system at RV may be a significant fraction of P_I,max. The recoil of the chest wall and lungs is equal at the functional residual capacity (FRC). The difference of values obtained from RV and FRC is not important in healthy subjects 1. In patients with neuromuscular disorders, the advantage of measuring the voluntary inspiratory strength from FRC is that only the force of the inspiratory muscles is assessed and not the negative recoil pressure of the respiratory system. Changing the reference in the text, as demonstrated in a study by Uldry et al. 2, is more suitable. Indeed, we used the predicted values of Uldry et al. 2 which were measured at FRC.

N.G Koulouris demonstrates that better values of inspiratory strength were obtained with a tube mouthpiece rather than a flanged mouthpiece in healthy subjects 3. Patients find the flanged mouthpiece easier than the tube explaining its widespead use 1. In our experience with neuromuscular disorders, especially in amyotrophic lateral sclerosis with bulbar involvement, air leaks were less important with a flanged mouthpiece 4.

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