Effects of incremental inspiratory load on inspiratory muscles activity in stroke subjects in comparison to healthy individuals

Aim: We assessed inspiratory muscles activation during incremental inspiratory loads in subjects with stroke and controls by surface electromyography (sEMG). Methods: Subjects of both genders with stroke diagnosis and healthy individuals were enrolled. Spirometry and maximal respiratory pressures were assessed. Incremental inspiratory load test was performed using Threshold® device and included progressive increase from 15%, 30%, 45% and 60% of maximal inspiratory pressure - MIP. Muscle activation of scalene - SCL, sternocleidomastoid-SCM and lowest intercostal space - LIS, related to diaphragm activity, was recorded by sEMG bilaterally. Results: Females with stroke showed decreased activity in SCM (15% of MIP) and SCL (15% of MIP and MIP) (p<0.05) compared to controls. Stroke males showed decreased diaphragm activity during 60% of MIP compared to controls (p<0.05). Muscle activity was decreased (p<0.05) in the paretic side compared to the healthy side in all muscles during different incremental loads and MIP, mainly in males. Conclusion: Incremental inspiratory loads were able to increase muscles activity in stroke subjects and controls, differently. Reduce the activity of paretic side inspiratory muscle suggests the influence of the disease on muscular activity.