Authors: Tzelepis, G. E.¹; Zakynthinos, S.²; Mandros, C.¹; Tzelepis, E.¹; Roussos, C.²

Source: Acta Physiologica, Volume 185, Number 3, November 2005 , pp. 251-256(6)

Publisher: Wiley-Blackwell

Abstract:

Aim: 

To test the hypothesis that the maximal inspiratory muscle (IM) performance, as assessed by the maximal IM pressure–flow relationship, is enhanced with the stretch-shortening cycle (SSC). Methods: 

Maximal inspiratory flow–pressure curves were measured in 12 healthy volunteers (35 ± 6 years) during maximal single efforts through a range of graded resistors (4-, 6-, and 8-mm diameter orifices), against an occluded airway, and with a minimal load (wide-open resistor). Maximal inspiratory efforts were initiated at a volume near residual lung volume (RV). The subjects exhaled to RV using slow (S) or fast (F) manoeuvres. With the S manoeuvre, they exhaled slowly to RV and held the breath at RV for about 4 s prior to maximal inspiration. With the F manoeuvre, they exhaled rapidly to RV and immediately inhaled maximally without a post-expiratory hold; a strategy designed to enhance inspiratory pressure via the SSC. Results: 

The maximal inspiratory pressure–flow relationship was linear with the S and F manoeuvres (r² = 0.88 for S and r² = 0.88 for F manoeuvre, P < 0.0005 in all subjects). With the F manoeuvre, the pressure–flow relationship shifted to the right in a parallel fashion and the calculated maximal power increased by approximately 10% (P < 0.05) over that calculated with the S manoeuvre. Conclusion: 

The maximal inspiratory pressure–flow capacity can be enhanced with SSC manoeuvres in a manner analogous to increases in the force–velocity relationship with SSC reported for skeletal muscles.

Keywords: force–velocity; power; pressure–flow; respiratory muscles

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1365-201X.2005.01486.x

Affiliations: 1: Department of Pathophysiology and Laiko General Hospital, University of Athens Medical School, Athens, Greece 2: Evangelismos Hospital and Department of Critical Care, University of Athens Medical School, Athens, Greece

Publication date: 2005-11-01

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