Biometric approximation of diaphragmatic contractility during sustained hyperpnea |
| |
Authors: | Kabitz Hans-Joachim Walker David Johannes Schwoerer Anja Schlager Daniel Walterspacher Stephan Storre Jan Hendrik Roecker Kai Windisch Wolfram Vergès Samuel Spengler Christina M |
| |
Affiliation: | a Department of Pneumology, University Hospital Freiburg, Killianstrasse 5 D, 79106, Germany;b Sports-Medicine, University Hospital Freiburg, Germany;c HP2 Laboratory (INSERM ERI17), Joseph Fourier University, Grenoble, France;d Exercise Physiology, Institute of Human Movement Sciences, ETH Zurich, Switzerland;e Institute of Physiology and Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland |
| |
Abstract: | Imposing load on respiratory muscles results in a loss of diaphragmatic contractility that develops early, is independent of task failure, and levels off following the initial decrease. This study assessed the progression of diaphragmatic contractility during sustained normocapnic hyperpnea and applied a biometric approximation (hypothesis: non-linear decay). Ten healthy subjects performed three consecutive hyperpnea bouts (I:6 min warm up/II:9 min/III:task failure 28.6 ± 11.5 min; mean ± SD) at maximal voluntary ventilation fractions (I:30-60%/II:70%/III:70%), followed by recovery periods (I:18 min/II:6 min/III:30 min). Twitch transdiaphragmatic pressure (TwPdi) was assessed throughout the protocol. Bouts II and III induced diaphragmatic fatigue (TwPdi baseline vs. Recovery -19 ± 17% and -30 ± 16%, both p < 0.05 RM-ANOVA) while bout I did not. During sustained hyperpnea (II/III), TwPdi followed an exponential decay (r(2) = 0.91). The reduction in diaphragmatic contractility closely follows a non-linear function with an early loss in diaphragmatic contractility during sustained hyperpnea, levels off thereafter, and is independent of task failure. Thus, reasons other than diaphragmatic fatigue are likely to be responsible for task failure during sustained hyperpnea. |
| |
Keywords: | Respiratory muscle Twitch transdiaphragmatic pressure Diaphragmatic fatigue |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|