Evolution of inspiratory and expiratory muscle pressures during endurance exercise
| Autor: | Colm McParland, Charles G. Gallagher, Bharath S. Krishnan, T. Zintel |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Adult
Male medicine.medical_specialty Time Factors Physiology Physical exercise Endurance training Physiology (medical) Internal medicine Pressure Tidal Volume Respiratory muscle Humans Medicine Expiration Respiratory system Exercise physiology Exercise Tidal volume business.industry Respiration Respiratory Muscles Linear Models Physical Endurance Physical therapy Cardiology Lung Volume Measurements Pulmonary Ventilation business Respiratory minute volume |
| Zdroj: | Journal of Applied Physiology. 88:234-245 |
| ISSN: | 1522-1601 8750-7587 |
| DOI: | 10.1152/jappl.2000.88.1.234 |
| Popis: | We investigated the relationship between minute ventilation (V˙e) and net respiratory muscle pressure (Pmus) throughout the breathing cycle [Total Pmus = mean Pmus, i (inspiratory) + mean Pmus, e(expiratory)] in six normal subjects performing constant-work heavy exercise (CWHE, at ∼80% maximum) to exhaustion on a cycle ergometer. Pmus was calculated as the sum of chest wall pressure (elastic + resistive) and pleural pressure, and all mean Pmus variables were averaged over the total breath duration. Pmus, i was also expressed as a fraction of volume-matched, flow-corrected dynamic capacity of the inspiratory muscles ([Formula: see text]).V˙e increased significantly from 3 min to the end of CWHE and was the result of a significantly linear increase in Total Pmus (Δ = 43 ± 9% from 3 min to end exercise, P < 0.005) in all subjects ( r = 0.81–0.99). Although mean Pmus, i during inspiratory flow increased significantly (Δ = 35 ± 10%), postinspiratory Pmus, i fell (Δ = −54 ± 10%) and postexpiratory expiratory activity was negligible or absent throughout CWHE. There was a greater increase in mean Pmus, e (Δ = 168 ± 48%), which served to increaseV˙e throughout CWHE. In five of six subjects, there were significant linear relationships betweenV˙eand mean Pmus, i( r = 0.50–0.97) and mean Pmus, e( r = 0.82–0.93) during CWHE. The subjects generated a wide range of Pmus, i/[Formula: see text]values (25–80%), and mean Pmus, i/[Formula: see text]increased significantly (Δ = 42 ± 16%) and in a linear fashion ( r = 0.69–0.99) withV˙ethroughout CWHE. The progressive increase inV˙e during CWHE is due to 1) a linear increase in Total Pmus, 2) a linear increase in inspiratory muscle load, and 3) a progressive fall in postinspiratory inspiratory activity. We conclude that the relationship between respiratory muscle pressure andV˙e during exercise is linear and not curvilinear. |
| Databáze: | OpenAIRE |
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