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Decreased lung capillary blood volume post-exercise is compensated by increased membrane diffusing capacity
D P Johns1, D Berry, M Maskrey
1Discipline of Medicine, School of Medicine, University of Tasmania, 7001 Hobart, Tasmania, Australia.
European Journal of Applied Physiology
|July 28, 2004
Summary
Intense exercise temporarily reduces lung diffusing capacity for carbon monoxide (DLCO) by decreasing pulmonary capillary blood volume (Vc), not due to edema. This suggests blood redistribution away from the lungs post-exercise.
Area of Science:
- Physiology
- Pulmonary Function Testing
- Exercise Science
Background:
- The diffusing capacity of the lung for carbon monoxide (DLCO) decreases post-intense exercise.
- Proposed mechanisms include pulmonary edema or reduced pulmonary capillary blood volume (Vc).
Purpose of the Study:
- To investigate the mechanisms behind post-exercise DLCO reduction.
- To measure DLCO, Vc, and membrane diffusing capacity (Dm) following maximal exercise.
Main Methods:
- Nine healthy females underwent maximal treadmill exercise.
- DLCO, Vc, and Dm were measured using a rebreathing method before and up to 24 hours post-exercise.
Main Results:
- DLCO decreased for 3 hours post-exercise, returning to baseline by 16 hours.
- Pulmonary capillary blood volume (Vc) significantly decreased by 21.2% at 3 hours.
- Membrane diffusing capacity (Dm) increased by 14.7% at 3 hours.
Conclusions:
- The increase in Dm suggests the DLCO fall is not due to edema or blood-gas barrier injury.
- Reduced DLCO is consistent with blood redistribution away from the lungs.
- Reciprocal changes in Dm and Vc indicate improved gas transfer despite reduced Vc, possibly due to red blood cell reorientation.