Inspiratory muscle training and respiratory sensation during treadmill exercise.

We studied whether inspiratory muscle training (IMT) changed respiratory sensation during exercise in 12 healthy women; IMT was performed twice daily, for 15 minutes, using a pressure threshold device and continued for 4 weeks. The inspiratory threshold was set to 30 percent of each individual's maximal inspiratory pressure (Pimax). Breathing effort was evaluated during a progressive exercise test using Borg scale. After IMT, both Pimax and maximal transdiaphragmatic pressure increased by 30 percent in the training group (p < 0.05) but did not change in the control group. Prior to IMT, the Borg score increased in proportion to exercise grade. The difference in the sensory score-exercise stage curves before and after IMT in the training group was not significant. No significant difference was noted in the relationship of the Borg score to minute ventilation before and after 4 weeks in either group. We concluded that IMT may not affect respiratory sensation during exercise in normal subjects, although IMT increases diaphragmatic strength.