I did a lit review last year on evidence of effortful exercise in ALS -- there is a very limited shred of evidence that *possibly* exercising inspiratory muscles to moderate -- NOT full -- effort could help maintain function. There are one or two studies currently underway on that topic. Myself, I will issue the occasional spirometer (inspiratory/expiratory) to pALS who have reasonably good baseline strength, and who agree to exercise only to moderate and not fatiguing capacity. I set the device at a level where they don't have to use excessive effort to accomplish the target. When respiratory function declines, I will usually advise to discontinue the exercises, though by that time pALS have usually stopped doing them spontaneously.