Relationship Between Electromyogram Spectrum Parameters and the Tension-Time Index During Incremental Exercise in Trained Subjects.

The inspiratory muscle tension-time index T (given by P/P x T/T) could be used to reliably assess inspiratory muscle activity during exercise. So far, the correlation between the T and diaphragmatic activity has not been measured and the T has not been compared with other measurements of the inspiratory muscle load such as the transdiaphragmatic pressure index or . In this study we hypothesize that the T measuring the mouth is a noninvasive reflection of the electromyographic activity of the diaphragm. We simultaneously measured T and surface EMG (SEMG) of 8 trained subjects at rest and during incremental exercise. The curvature of T and the root mean square (RMS) follow the same trend during the incremental exercise with a significant correlation between T and surface EMG parameters (RMS; r = 0.81 p < 0.001 and MPF; r = 0.80 p < 0.001 respectively). We conclude that T measured as s an adequate noninvasive method reflects the diaphragmatic activity during incremental exercise in healthy subjects.