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Oxygen cost of exercise hyperpnea is greater in women compared to men (882.3)
Author(s) -
Dominelli Paolo,
Render Jacqueline,
MolgatSeon Yannick,
Foster Glen,
Romer Lee,
Sheel A
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.882.3
Subject(s) - hyperpnea , hyperventilation , medicine , cardiorespiratory fitness , work of breathing , tidal volume , respiratory minute volume , ventilation (architecture) , cardiology , respiratory rate , heart rate , physical therapy , respiratory system , anesthesia , blood pressure , mechanical engineering , engineering
We tested the hypothesis that the O2 cost of exercise hyperpnea is greater in women compared to men. Healthy subjects (8M, 7F) first performed a maximal step cycle exercise test with esophageal and gastric balloon instrumentation followed by a hyperpnea familiarization trial on a separate day. Cardiorespiratory parameters were measured and flow‐ and pressure‐volume loops were constructed from the same breaths (~n=10) for each exercise stage. Days 3 and 4 involved exercise hyperpnea mimicking over 5 ventilatory levels while in the cycling position. Mimicking trials were repeated (n=4) for each ventilatory level. End‐tidal CO2 was controlled to a level corresponding to each exercise stage. Respiratory muscle O2 uptake (VO2rm) was linearly related to work of breathing (WOB) in men (r=0.94, P<0.001) and women (r=0.88, P<0.001). The VO2rm to VE relationship was assessed by fitting a regression accounting for viscous and resistive work. There was no difference in viscous work (P=0.45); however, the resistive component was ~13x greater in women (P<0.05). At maximal ventilation the absolute VO2rm was similar between sexes (0.39 vs. 0.42 l min‐1, P=0.52) despite men having a greater VE (108 vs. 169 l min‐1); but the VO2rm represented a greater fraction of whole‐body VO2 in women (14.6 vs. 9.8%, P<0.05). In conclusion, the O2 cost of exercise hyperpnea is greater in women owing to a greater resistive WOB. Grant Funding Source : Natural Sciences and Engineering Research Council of Canada