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 cmH(2)O (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 cmH(2)O (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 cmH(2)O (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.