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Exercise‐induced quadriceps muscle fatigue in men and women: effects of arterial oxygen content and respiratory muscle work
Author(s) -
Dominelli Paolo B.,
MolgatSeon Yannick,
Griesdale Donald E. G.,
Peters Carli M.,
Blouin JeanSébastien,
Sekhon Mypinder,
Dominelli Giulio S.,
Henderson William R.,
Foster Glen E.,
Romer Lee M.,
Koehle Michael S.,
Sheel A. William
Publication year - 2017
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jp274068
Subject(s) - medicine , work of breathing , respiratory system , breathing , physical therapy , muscle fatigue , respiratory rate , cardiology , respiration , quadriceps muscle , physical medicine and rehabilitation , heart rate , anesthesia , electromyography , blood pressure , anatomy
Key points High work of breathing and exercise‐induced arterial hypoxaemia (EIAH) can decrease O 2 delivery and exacerbate exercise‐induced quadriceps fatigue in healthy men. Women have a higher work of breathing during exercise, dedicate a greater fraction of whole‐bodyV ̇ O 2towards their respiratory muscles and develop EIAH. Despite a greater reduction in men's work of breathing, the attenuation of quadriceps fatigue was similar between the sexes. The degree of EIAH was similar between sexes, and regardless of sex, those who developed the greatest hypoxaemia during exercise demonstrated the most attenuation of quadriceps fatigue. Based on our previous finding that women have a greater relative oxygen cost of breathing, women appear to be especially susceptible to work of breathing‐related changes in quadriceps muscle fatigue.Abstract Reducing the work of breathing or eliminating exercise‐induced arterial hypoxaemia (EIAH) during exercise decreases the severity of quadriceps fatigue in men. Women have a greater work of breathing during exercise, dedicate a greater fraction of whole‐bodyV ̇ O 2towards their respiratory muscles, and demonstrate EIAH, suggesting women may be especially susceptible to quadriceps fatigue. Healthy subjects (8 male, 8 female) completed three constant load exercise tests over 4 days. During the first (control) test, subjects exercised at ∼85% of maximum while arterial blood gases and work of breathing were assessed. Subsequent constant load exercise tests were iso‐time and iso‐work rate, but with EIAH prevented by inspiring hyperoxic gas or work of breathing reduced via a proportional assist ventilator (PAV). Quadriceps fatigue was assessed by measuring force in response to femoral nerve stimulation. For both sexes, quadriceps force was equally reduced after the control trial (−27 ± 2% baseline) and was attenuated with hyperoxia and PAV (−18 ± 1 and −17 ± 2% baseline, P < 0.01, respectively), with no sex difference. EIAH was similar between the sexes, and regardless of sex, subjects with the lowest oxyhaemoglobin saturation during the control test had the greatest quadriceps fatigue attenuation with hyperoxia ( r 2 = 0.79, P < 0.0001). For the PAV trial, despite reducing the work of breathing to a greater degree in men (men: 60 ± 5, women: 75 ± 6% control, P < 0.05), the attenuation of quadriceps fatigue was similar between the sexes (36 ± 4 vs . 37 ± 7%). Owing to a greater relativeV ̇ O 2of the respiratory muscles in women, less of a change in work of breathing is needed to reduce quadriceps fatigue.