Inspiratory muscle endurance testing: Pulmonary ventilation and electromyographic analysis

This study analyzed regional pulmonary ventilation and electromyographic (EMG) activity of the respiratory muscles during an inspiratory muscle endurance (IME) test in 10 young women. Radioaerosol (99mTc-DTPA) was generated using a jet nebulizer connected to a linear inspiratory loading system. The lung scintigraphic analysis showed an increase in the radioaerosol deposition using loads of 20 and 30 cmH2O (p < 0.01). The vertical gradient showed a larger radioaerosol deposition in the medium third of the lungs during the control period (p < 0.001). There were larger amounts of radioaerosol deposition in the medium third when compared with the upper and lower third at 30 cmH2O (p < 0.001). The horizontal gradient showed a larger deposition in the intermediate and central segments during all phases (p < 0.00). Electromyographic activity from the muscles of the lower rib cage increased with loads of 20 and 30 cmH2O (p < 0.03). There was an increase in deposition of radioaerosol when the load increased (r = 0.584, p = 0.000 for the left lung and r = 0.609, p = 0.000 for right lung). These findings suggest that during the IME test, EMG activity in the muscles of the lower rib cage increase during progressive respiratory workloads is associated with a greater radioaerosol deposition in the medium third and intermediate and central segments of the lungs.