Noninvasive measurement of respiratory muscle performance after exhaustive endurance exercise

Abstract

The use of noninvasive techniques to measure respiratory muscle performance after different types of endurance exercise has not been entirely successful, as the results have not consistently indicated diminished performance for similar types of exercise. The aim of the present study was 1) to compare different, noninvasive methods to assess respiratory muscle performance before and after an exhaustive cycling endurance test (which has previously been shown to induce diaphragmatic fatigue) and 2) to determine which of the tests best reflect published results of measurements of diaphragmatic fatigue.Twelve healthy subjects participated in the study and performed three different test series in a random order on three different days. These tests were performed before, and 5, 40 and 75 min after an exhausting task (a cycling endurance run at 85% of maximal oxygen uptake (V 'O 2 ,max)). The tests of the three test series were 1) breathing against a constant inspiratory resistance to task failure, 2) determination of 12-min sustained ventilatory capacity, and 3) spirometric and maximal inspiratory and expiratory mouth pressure measurements.The only measurement that was affected by exhaustive cycling was the time to task failure breathing against inspiratory resistance. It was significantly reduced from (meanSD) 36488 s before exercise to 219122 s at 5 min after cessation of exercise.It is concluded that the constant-load resistive breathing test to task failure is the only noninvasive respiratory muscle performance test evaluated in this study which shows a decrease in respiratory muscle performance after exhaustive endurance exercise.

Expiratory muscle fatigue impairs exercise performance

“…Similar to previous studies (O 'Kroy et al 1992;Perret et al 1999), intensive exercise per se did not induce a signiWcant change in PI max (CON-EX). However, PI max was reduced by 7% after expiratory resistive breathing.…”

“…In the course of exhaustive high-intensity exercise (¸85% of maximal oxygen consumption), inspiratory muscles are known to fatigue (Johnson et al 1993;Mador et al 1993;Perret et al 1999Perret et al , 2000 but also, expiratory muscle fatigue (EMF) was recently shown to develop under similar conditions (Taylor et al 2006;Verges et al 2006b). Expiratory muscles may be even more prone to fatigue than inspiratory muscles as several studies have shown that expiratory muscles are in general less oxidative than S. Verges · Y. Sager · C. Erni · C. M. Spengler Institute of Physiology and Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland inspiratory muscles (Lieberman et al 1973;Uribe et al 1992) and are therefore expected to be less fatigue resistant.…”

A comparison of inspiratory muscle fatigue following maximal exercise in moderately trained males and females

“…However, these findings are still disputed. A number of studies have not been able to show these similar results (Coast et al 1990;Johnson et al 1993;Perret et al 1999). Also, whole body endurance exercise in healthy subjects has been shown to cause diaphragmatic fatigue in a wide range of fitness levels (Johnson et al 1993).…”

Task failure from inspiratory resistive loaded breathing: a role for inspiratory muscle fatigue?

“…Taking into account these points the question still remains of whether task failure, under these conditions, is a good measure for inspiratory muscle fatigue. We previously found that subjects breathing at a constant load ($80% maximal inspiratory pressure; MIP) with paced respiratory frequency (f R ) and duty cycle until task failure can breathe for the same duration with only a 15-min break after the first run (Perret et al 1999).…”