Non-Invasive Ventilation Applied for Recovery from Exercise-Induced Diaphragmatic Fatigue



Hans-Joachim Kabitz*, a, David Walkera, Stephan Prettinb, Stephan Walterspachera, Florian Sonntaga, Michael Drehera, Wolfram Windischa
Department of Pneumologya, University Hospital Freiburg, Killianstrasse 5, D-79106 Freiburg, Germany
Department of Sports-Medicine,University Hospital Freiburg, Killianstrasse 5, D-79106 Freiburg, Germany


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2008 Bentham Science Publishers Ltd.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.5/), which permits unrestrictive use, distribution, and reproduction in any medium, provided the original work is properly cited.

* Address correspondence to this author at the Department of Pneumology, University Hospital Freiburg, Killianstrasse 5, D-79106 Freiburg, Germany; Tel: +49 761 270-3706; Fax: +49 761 270-3704;E-mail: hans-joachim.kabitz@uniklinik-freiburg.de


Abstract

Background

Exercise-induced diaphragmatic fatigue (DF) is conventionally considered to reflect impaired diaphragm function resulting from load imposed on the diaphragm during exercise and is known to be reduced by the application of non-invasive ventilation (NIV) during heavy-intensity exercise testing (HEET). On that physiological condition NIV applied for diaphragm unloading during recovery from exercise should be capable of accelerating recovery from DF and therewith prolonging exercise time to exhaustion and limiting the development of DF during a subsequent HEET compared to recovery during spontaneous breathing.

Methods

Seven highly-trained subjects (V’O2max 62.7±7.8 ml/kg/min) performed four HEET at 85% V’O2max with 60 min of recovery during I spontaneous breathing and II NIV between two HEET.

Results

Twitch transdiaphragmatic pressure (TwPdi) during supramaximal magnetic phrenic nerve stimulation decreased (p<0.04) following first HEET and subsequently completely recovered (p>0.2) during I and II. Following second HEET TwPdi comparably decreased (I 0.24±0.21 vs II 0.32±0.29 kPa; p=0.17). Exercise time to exhaustion during second HEET was equal during I and II (I 514±49 vs II 511±92 s; p=0.88).

Conclusions

In conclusion, NIV applied for diaphragm unloading during recovery following HEET does neither affect recovery from DF nor subsequent exercise performance thereby providing further evidence that DF might reflect post-exercise diaphragm shielding rather than impaired diaphragm function.

Keywords: Inspiratory muscles, twitch pressures, exercise testing, ergospirometry, respiratory physiology.