title: The heterogeneity of regional specific ventilation is unchanged following heavy exercise in athletes.
abstract: Heavy exercise increases ventilation-perfusion mismatch and decreases pulmonary gas exchange efficiency. Previous work using magnetic resonance imaging (MRI) arterial spin labeling in athletes has shown that, after 45 min of heavy exercise, the spatial heterogeneity of pulmonary blood flow was increased in recovery. We hypothesized that the heterogeneity of regional specific ventilation (SV, the local tidal volume over functional residual capacity ratio) would also be increased following sustained exercise, consistent with the previously documented changes in blood flow heterogeneity. Trained subjects (n = 6, maximal O2 consumption = 61 ± 7 ml·kg(-1)·min(-1)) cycled 45 min at their individually determined ventilatory threshold. Oxygen-enhanced MRI was used to quantify SV in a sagittal slice of the right lung in supine posture pre- (preexercise) and 15- and 60-min postexercise. Arterial spin labeling was used to measure pulmonary blood flow in the same slice bracketing the SV measures. Heterogeneity of SV and blood flow were quantified by relative dispersion (RD = SD/mean). The alveolar-arterial oxygen difference was increased during exercise, 23.3 ± 5.3 Torr, compared with rest, 6.3 ± 3.7 Torr, indicating a gas exchange impairment during exercise. No significant change in RD of SV was seen after exercise: preexercise 0.78 ± 0.15, 15 min postexercise 0.81 ± 0.13, 60 min postexercise 0.78 ± 0.08 (P = 0.5). The RD of blood flow increased significantly postexercise: preexercise 1.00 ± 0.12, 15 min postexercise 1.15 ± 0.10, 45 min postexercise 1.10 ± 0.10, 60 min postexercise 1.19 ± 0.11, 90 min postexercise 1.11 ± 0.12 (P < 0.005). The lack of a significant change in RD of SV postexercise, despite an increase in the RD of blood flow, suggests that airways may be less susceptible to the effects of exercise than blood vessels.
authors: School of Exercise and Nutritional Sciences, San Diego State University, San Diego, California, USA.
authors: Vince
authors: V
authors: Tedjasaputra
authors: Rui Carlos
authors: RC
authors: Sá
authors: Tatsuya J
authors: TJ
authors: Arai
authors: Sebastiaan
authors: S
authors: Holverda
authors: Rebecca J
authors: RJ
authors: Theilmann
authors: William T
authors: WT
authors: Chen
authors: Peter D
authors: PD
authors: Wagner
authors: Christopher K
authors: CK
authors: Davis
authors: G
authors: G
authors: Kim Prisk
authors: Susan R
authors: SR
authors: Hopkins
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D001784:Blood Gas Analysis; D001834:Body Water / Q000378:metabolism; D003627:Data Interpretation, Statistical; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008168:Lung / Q000033:anatomy & histology* / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D011652:Pulmonary Circulation / Q000502:physiology; D011659:Pulmonary Gas Exchange; D015656:Respiratory Mechanics / Q000502:physiology*; D013147:Spirometry; D014692:Ventilation-Perfusion Ratio; D014797:Vital Capacity / Q000502:physiology; D055815:Young Adult
keywords: lung imaging; magnetic resonance imaging; pulmonary gas exchange; ventilation-perfusion mismatch
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