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[Purpose] The aim of this study was to reveal the effect of expiratory muscle fatigue (EMF) on respiratory response under two different exercise conditions: exercise (EX) with EMF (EMF-EX) and control EX without EMF (CON-EX). [Methods] Nine healthy adult men performed cycle exercise with a ramp load, and a spirometer was used to measure forced vital capacity (FVC), forced expiratory volume in one second, percent of forced expiratory volume, maximal expiratory mouth pressure, and maximal inspiratory mouth pressure (PImax) to evaluate respiratory functions immediately and at 15 and 30 min after exercise. To assess the respiratory response during exercise, an exhaled gas analyzer was used to measure minute ventilation (VE), respiratory frequency (f), tidal volume (VT), oxygen uptake, and carbon dioxide output. In addition, the Borg Scale was used to evaluate dyspnea, while electrocardiography was used to measure heart rate. [Results] The results showed that compared with the CON-EX condition, no change in VE, an increase in f, or a decrease in VT was observed under the medium-intensity EMF-EX condition, while high-intensity exercise reduced VE and f without changing VT. [Conclusion] These results suggest that during medium-intensity exercise, EMF modulates the respiratory response by inducing shallow and fast breathing to increase ventilation volume.

We have investigated, in six healthy male volunteers, the effect of high thoracic extradural anaesthesia on the ventilatory pattern and hypercapnic ventilatory response. Ventilatory variables were determined using a respiratory inductive plethysmograph. Duration of inspiration, rib cage excursion and its contribution to tidal volume decreased significantly following extradural anaesthesia, while mean inspiratory flow rate and minute ventilation increased. End-tidal PCO2 and the tidal excursion of the abdomen were unchanged. Hypercapnic ventilatory response decreased significantly following extradural anaesthesia, principally because of the rib cage component. The slope of the abdominal component did not change significantly. The results indicate that mechanical impairment of rib cage movement can produce decreased ventilatory response to carbon dioxide. The ventilatory impairment and the changes in breathing pattern induced by the high thoracic extradural anaesthesia probably reflect blockade of the efferent or afferent pathway (or both) of the intercostal nerve roots.

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We found that using a mouse in the DP rather than the PP leads to less activity of the external rotators, less perceived fatigue and more productivity. This suggests that the DP is preferable to the PP for computer work involving a mouse.