Inspiratory Strengthening Effect on Resistive Load Detection and Magnitude Estimation

Purpose: This study investigated effects of inspiratory muscle training (IMT) on maximal inspiratory pressure (MIP), magnitude estimation (ME), and load detection (LD) of external resistive loads (deltaR) in healthy subjects.

Methods: Ten adult volunteers IMT trained 5 d x wk(-1) for 4 wk. A training set consisted of six inspiratory efforts at 75% of MIP; daily training trials consisted of four sets. ME was calculated by linear regression, with actual and estimated deltaR loads plotted on log-log scale. LD was calculated by determining deltaR50/Ro fraction. Dependent measures were taken pre- and post-IMT.

Results: MIP significantly increased from 87 to 139 cmH2O pre- to post-IMT, respectively. ME for individual loads significantly decreased post-IMT for all but the highest deltaR. There was no significant difference in LD deltaR50/Ro, post-IMT.

Conclusions: The results demonstrate that inspiratory muscle strength gains were associated with decreased ME of deltaRs without changing LD deltaR50/Ro. This suggests that the mechanisms mediating the detection of deltaRs may be different than the mechanisms for estimating deltaR size.