Impaired pulmonary VO2 kinetics in cystic fibrosis depend on exercise intensity
Impaired pulmonary VO2 kinetics in cystic fibrosis depend on exercise intensity
Purpose: to investigate the effects of mild-to-moderate cystic fibrosis (CF) on the pulmonary oxygen uptake (VO2) kinetics of 7 pediatric patients (13.5 +/- 2.8 y) versus 7 healthy matched controls (CON; 13.6 +/- 2.4 y). We hypothesized that CF would slow the VO2 kinetic response at the onset of moderate (MOD) and very heavy (VH) intensity cycling.
Methods: changes in breath-by-breath VO2, near-infrared spectroscopy-derived muscle deoxygenation ([HHb]) at the m. vastus lateralis and thoracic bioelectrical impedance-derived heart rate, stroke volume index (SVI) and cardiac index (CI) were measured during repeat transitions to MOD (90% of the gas exchange threshold) and VH (Δ60%) intensity cycling exercise.Results - During MOD, the phase II VO2 [tau] (p=0.84; effect size (ES) = 0.11) and overall mean response time (MRT) (p=0.52; ES=0.11) were not significantly slower in CF versus CON. However, during VH exercise, the phase II VO2 [tau] (p=0.02, ES=1.28) and MRT (p=0.01, ES=1.40) were significantly slower in CF. Cardiac function, central O2 delivery (SVI and CI) and muscle [HHb] kinetics were unaltered in CF. However, the arterial-venous O2 content difference (C(a-v)O2) was reduced during VH at 30 s (p=0.03, ES=0.37), with a trend for reduced levels at 0 s (p=0.07, ES=0.25), 60 s (p=0.05, ES=0.28) and 120 s (p=0.07, ES=0.25) in CF. Furthermore, ΔC(a-v)O2 significantly correlated with the VH phase II VO2 [tau] (r= -0.85; p=0.02) and MRT (r = -0.79; p=0.03) in CF only.
Conclusion: impairments in muscle oxidative metabolism during constant work rate exercise are intensity-dependent in young people with mild-to-moderate CF. Specifically, VO2 kinetics are slowed during VH but not MOD cycling and appear to be mechanistically linked to impaired muscle O2 extraction and utilization.
oxidative muscle metabolism, pulmonary disease, near-infrared spectroscopy, oxygen delivery, pediatrics
2090-2099
Saynor, Zoe Louise
a4357c7d-db59-4fa5-b24f-58d2f7e74e39
Barker, Alan Robert
4e993530-deda-42e5-b3fd-c96f63b44fe6
Oades, Patrick John
8eb36d46-5002-4257-a502-d06384480d69
Williams, Craig Anthony
896d5d83-8313-4207-a26f-28b74acb790c
1 November 2016
Saynor, Zoe Louise
a4357c7d-db59-4fa5-b24f-58d2f7e74e39
Barker, Alan Robert
4e993530-deda-42e5-b3fd-c96f63b44fe6
Oades, Patrick John
8eb36d46-5002-4257-a502-d06384480d69
Williams, Craig Anthony
896d5d83-8313-4207-a26f-28b74acb790c
Saynor, Zoe Louise, Barker, Alan Robert, Oades, Patrick John and Williams, Craig Anthony
(2016)
Impaired pulmonary VO2 kinetics in cystic fibrosis depend on exercise intensity.
Medicine and Science in Sports and Exercise, 48 (11), .
(doi:10.1249/MSS.0000000000001004).
Abstract
Purpose: to investigate the effects of mild-to-moderate cystic fibrosis (CF) on the pulmonary oxygen uptake (VO2) kinetics of 7 pediatric patients (13.5 +/- 2.8 y) versus 7 healthy matched controls (CON; 13.6 +/- 2.4 y). We hypothesized that CF would slow the VO2 kinetic response at the onset of moderate (MOD) and very heavy (VH) intensity cycling.
Methods: changes in breath-by-breath VO2, near-infrared spectroscopy-derived muscle deoxygenation ([HHb]) at the m. vastus lateralis and thoracic bioelectrical impedance-derived heart rate, stroke volume index (SVI) and cardiac index (CI) were measured during repeat transitions to MOD (90% of the gas exchange threshold) and VH (Δ60%) intensity cycling exercise.Results - During MOD, the phase II VO2 [tau] (p=0.84; effect size (ES) = 0.11) and overall mean response time (MRT) (p=0.52; ES=0.11) were not significantly slower in CF versus CON. However, during VH exercise, the phase II VO2 [tau] (p=0.02, ES=1.28) and MRT (p=0.01, ES=1.40) were significantly slower in CF. Cardiac function, central O2 delivery (SVI and CI) and muscle [HHb] kinetics were unaltered in CF. However, the arterial-venous O2 content difference (C(a-v)O2) was reduced during VH at 30 s (p=0.03, ES=0.37), with a trend for reduced levels at 0 s (p=0.07, ES=0.25), 60 s (p=0.05, ES=0.28) and 120 s (p=0.07, ES=0.25) in CF. Furthermore, ΔC(a-v)O2 significantly correlated with the VH phase II VO2 [tau] (r= -0.85; p=0.02) and MRT (r = -0.79; p=0.03) in CF only.
Conclusion: impairments in muscle oxidative metabolism during constant work rate exercise are intensity-dependent in young people with mild-to-moderate CF. Specifically, VO2 kinetics are slowed during VH but not MOD cycling and appear to be mechanistically linked to impaired muscle O2 extraction and utilization.
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Accepted/In Press date: May 2016
Published date: 1 November 2016
Keywords:
oxidative muscle metabolism, pulmonary disease, near-infrared spectroscopy, oxygen delivery, pediatrics
Identifiers
Local EPrints ID: 494272
URI: http://eprints.soton.ac.uk/id/eprint/494272
ISSN: 0195-9131
PURE UUID: 2c43fab7-848f-4385-ac4a-29d50557fb51
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Date deposited: 03 Oct 2024 16:33
Last modified: 04 Oct 2024 02:10
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Author:
Zoe Louise Saynor
Author:
Alan Robert Barker
Author:
Patrick John Oades
Author:
Craig Anthony Williams
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