Influence of body position on muscle deoxy[Hb+Mb] during ramp cycle exercise

Respiratory Physiology & Neurobiology
Fred J DimennaAndrew M Jones

Abstract

We used near-infrared spectroscopy (NIRS) to test the hypothesis that body position alters the sigmoidal response profile of muscle fractional O(2) extraction (estimated using deoxy[Hb+Mb]) during incremental cycle exercise. Seven male subjects (mean±SD age 32±13 years) completed a ramp incremental cycling test to exhaustion (30W/min) in both the supine and upright body positions. The sigmoidal (as opposed to hyperbolic) model that provided the better fit to deoxy[Hb+Mb] data during upright cycling was also present for the supine response; however, the slope of the sigmoid was increased (upright: 0.052±0.012 vs. supine: 0.090±0.036%⋅%P(peak)(-1); P<0.05) and a plateau occurred at a lower work rate (upright: 83±8 vs. supine: 68±19%P(peak)(-1); P<0.05) during supine exercise. These changes occurred in the absence of a leftward shift of the sigmoid. We also found a significantly greater deltaV(O)₂/deltaW slope above compared to below gas exchange threshold (GET) for both conditions (upright: 9.8±0.5 vs. 8.2±0.9; supine: 10.7±0.9 vs. 8.0±0.8) and for supine compared to upright cycling above GET. These findings suggest that the supine posture affects O₂ extraction and V(O)₂ kinetics to a greater extent as work rate progresses during...Continue Reading

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Citations

Jul 19, 2011·European Journal of Applied Physiology·Jan BooneJan Bourgois
Jan 25, 2012·European Journal of Applied Physiology·Matthew D SpencerDonald H Paterson
Sep 3, 2013·Respiratory Physiology & Neurobiology·Juan M MuriasDonald H Paterson
May 15, 2013·Respiratory Physiology & Neurobiology·C J AdeT J Barstow
Jan 7, 2017·Obesity·Alessandro da Costa MachadoBruno Moreira Silva
Jan 1, 2015·Medicine and Science in Sports and Exercise·Melitta A McNarryAlan R Barker
Dec 19, 2019·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Rafael de Almeida AzevedoJuan M Murias
Sep 27, 2014·Journal of Applied Physiology·Matthew D SpencerShunsaku Koga
Jun 3, 2011·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Shunsaku KogaThomas J Barstow
Nov 9, 2012·Medicine and Science in Sports and Exercise·Mikel EgañaSteven O'Donnell
Jun 29, 2021·Frontiers in Sports and Active Living·Anja WehrleKai Roecker
Aug 26, 2021·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Richie P GouldingShunsaku Koga
Oct 29, 2021·Frontiers in Cardiovascular Medicine·Xiaohua WanWei Jiang

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