Effects of expiratory threshold loading during steady-state exercise.

Journal of Applied Physiology
I GoldsteinN R Anthonisen

Abstract

Increases in functional residual capacity (FRC) decrease inspiratory muscle efficiency; the present experiments were designed to determine the effect of FRC change on the ventilatory response to exercise. Six well-trained adults were exposed to expiratory threshold loads (ETL) ranging from 5 to 40 cmH2O during steady-state exercise on a bicycle ergometer at 40-95% VO2max. Inspiratory capacity (IC) was measured and changes of IC interpreted as changes of FRC. ETL did not consistently limit exercise performance. At heavy work (greater than 92% VO2max) minute ventilation decreased with increasing ETL; at moderate work (less than 58% VO2max) it did not. Decreases in ventilation were due to decreases in respiratory frequency with prolongation of the duration of expiration being the most consistent change in breathing pattern. At moderate work levels, FRC increased with ETL; at maximum work it did not. Changes in FRC were dictated by constancy of tidal volume and a fixed maximum end-inspiratory volume of 80-90% of the inspiratory capacity. When tidal volume was such that end-inspiratory volume was less than this value, FRC increased with ETL. Mouth pressure measured during the first 0-1 s of inspiratory effort against an occluded air...Continue Reading

Citations

Jan 28, 1998·American Journal of Respiratory and Critical Care Medicine·R PellegrinoM B Reid
Jul 1, 1988·Acta Physiologica Scandinavica·T B Barnett, B Rasmussen
Jan 20, 2004·Journal of Applied Physiology·Kristy N Stark-LeyvaBruce D Johnson
Jun 9, 2020·Frontiers in Physiology·Tina Dysgaard Jeppesen
May 29, 2015·PloS One·Teresa PittsDonald C Bolser
Apr 10, 2007·Respiratory Physiology & Neurobiology·Chi-Sang PoonYunguo Yu

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