World Library  
Flag as Inappropriate
Email this Article

Respiratory exchange ratio

Article Id: WHEBN0007939119
Reproduction Date:

Title: Respiratory exchange ratio  
Author: World Heritage Encyclopedia
Language: English
Subject: Respiratory quotient, Alveolar gas equation, RER, RĂ©seau Express RĂ©gional, Fraction of inspired oxygen
Collection: Respiration
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Respiratory exchange ratio

The respiratory exchange ratio (RER) is the ratio between the amount of oxygen (O2) consumed and carbon dioxide (CO2) produced in one breath. Humans typically inhale more molecules of oxygen than they exhale of carbon dioxide.

The ratio is determined by comparing exhaled gasses to room air. Measuring this ratio can be used for estimating the respiratory quotient (RQ), an indicator of which fuel (carbohydrate or fat) is being metabolized to supply the body with energy. This estimation is only valid if metabolism is in a steady state.

RER is about 0.8 at rest with a modern diet. This value however, can exceed 1 during intense exercise, as CO2 production by the working muscles becomes greater and more of the inhaled O2 gets used rather than being expelled. During moderate or higher intensity aerobic exercise and anaerobic exercise, using RER for estimating RQ loses accuracy because of factors including bicarbonate buffering of hydrogen ions, which affects the CO2 levels being expelled by the respiratory system.

Calculation of RER is commonly done in conjunction with exercise tests such as the VO2 Max Test and can be used as an indicator that the participants are nearing exhaustion and the limits of their cardio-respiratory system. An RER greater than 1.1 is often used as a secondary endpoint criterion of a VO2 Max Test.

An RER of 0.70 indicates that fat is the predominant fuel source, RER of 0.85 suggests a mix of fat and carbohydrates, and a value of 1.00 or above is indicative of carbohydrate being the predominant fuel source.

Oxidation of a molecule of Carbohydrate 6 O2 + C6H12O6=>6 CO2 + 6 H2O + 38 ATP RER = VCO2/VO2 = 6 CO2/6 O2 = 1.0

Oxidation of a molecule of Fatty Acid 23 O2 + C16H32O2=>16 CO2 + 16 H2O + 129 ATP RER = VCO2/VO2 =

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 



Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.