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Impaired Pulmonary ...O2 Kinetics in Cystic Fibrosis Depend on Exercise Intensity.
- Source :
-
Medicine & Science in Sports & Exercise . Nov2016, Vol. 48 Issue 11, p2090-2099. 10p. - Publication Year :
- 2016
-
Abstract
- Purpose: This study aimed to investigate the effects of mild-to-moderate cystic fibrosis (CF) on the pulmonary oxygen uptake (...O2) kinetics of seven pediatric patients (13.5 ± 2.8 yr) versus seven healthy matched controls (CON; 13.6 ± 2.4 yr). We hypothesized that CF would slow the ...O2 kinetic response at the onset of moderate (MOD) and very heavy (VH) intensity cycling. Methods: Changes in breath-by-breath ...O2, near-infrared spectroscopy-derived muscle deoxygenation ([HHb]) at the vastus lateralis muscle and thoracic bioelectrical impedance--derived heart rate (HR), stroke volume index, and cardiac index 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 ...O2 τ (P = 0.84, effect size [ES] = 0.11) and the 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...O2 τ (P = 0.02, ES = 1.28) and MRT (P = 0.01, ES = 1.40) were significantly slower in CF. Cardiac function, central O2 delivery (stroke volume index and cardiac index), and muscle [HHb] kinetics were unaltered in CF. However, the arteriovenous O2 content difference (C(a-...y)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-...)O2 significantly correlated with the VH phase II...O2 τ (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, ...O2 kinetics are slowed during VH but not MOD cycling and appear to be mechanistically linked to impaired muscle O2 extraction and utilization. [ABSTRACT FROM AUTHOR]
- Subjects :
- *LUNG physiology
*COMPARATIVE studies
*CYCLING
*CYSTIC fibrosis
*DYNAMICS
*ENERGY metabolism
*HEART beat
*BIOELECTRIC impedance
*NEAR infrared spectroscopy
*REACTION time
*QUADRICEPS muscle
*OXYGEN consumption
*CASE-control method
*EXERCISE intensity
*STROKE volume (Cardiac output)
*DISEASE complications
Subjects
Details
- Language :
- English
- ISSN :
- 01959131
- Volume :
- 48
- Issue :
- 11
- Database :
- Academic Search Index
- Journal :
- Medicine & Science in Sports & Exercise
- Publication Type :
- Academic Journal
- Accession number :
- 118901553
- Full Text :
- https://doi.org/10.1249/MSS.0000000000001004