Respiratory muscle electrical activity during nasal respiratory strength test in different positions in ALS and health subjects

Compare the electromyographic activity of the respiratory muscles during the SNIP and SNEP maneuvers in a sitting position and inclined at 45º. Subjects with ALS and age-matched control group. Spirometry, surface electromyography (EMGs) of the sternocleidomastoid, scalene, rectus abdominis and external oblique muscles were evaluated during maximal respiratory pressure maneuvers (MIP and MEP) in a sitting position and nasal pressures breathing (SNIP and SNEP) in the sitting and inclined at 45º position (randomized). Twenty male individuals, 9 healthy (43.6 ± 11.6 years) and 11 with ALS (46.8 ± 12.5 years) were evaluated. Pulmonary function in subjects with ALS presents FVC (%pred) of 78.7 ± 18 and FEV₁/FVC ratio of 0.79 ± 0.07 and in healthy subjects FVC (%pred) of 83.1 ± 17.9% and FEV₁/FVC ratio of 0.84 ± 0.12. In subjects with ALS, the basal electromyographic activity of the ECM, at rest and during SNIP, was higher than that of healthy subjects in both positions (p<0.05). No significant differences were found in electrical activity in the other variables and measurements. SNEP values in the inclined position were lower than in the sitting position in subjects with ALS (70.3 ± 26.7 <italic>vs.</italic> 57.3 ± 22.8 cmH₂O, p<0.05). SNIP and SNEP were lower in subjects with ALS in the 45º inclined position <italic>vs</italic>. healthy subjects (69.1 ± 2.72 <italic>vs</italic>. 95.5 ± 23.5 cmH₂O; 57.3 ± 22.5 <italic>vs.</italic> 92.7 ± 26.4 cmH₂O, p<0.05, respectively). Subjects with ALS showed lower respiratory muscle strength values when compared to healthy subjects. Basal ECM muscle electrical activity was higher in the ALS group in boths positions.