Response of Normal Man to Graded Exercise in Progressive Elevations of CO2
Abstract
Trained volunteers performed steady-state moderate exercise (one-half of maximum VO2) and heavy exercise (two-thirds of maximum VO2) in 0, 8, 15, 21, and 30 mm. Hg PICO2 for 30 minutes on a bicycle ergometer. At CO2 levels of 8 and 15 mm. Hg, no difficulty was encountered by the subjects. The higher levels of hypercapnia caused some respiratory symptoms of "air-hunger" and intercostal muscle pain, but were of mild enough degree to permit all subjects to complete the exercise. Incremental exercise up to workloads producing maximum VO2 was also performed. The tolerance at maximum exercise in 21 mm. Hg PICO2 resembled that at two-thirds workload in 30 mm. Hg PICO2. VE during maximum exercise did not vary with the level of inspired CO2, whereas at submaximal workloads, VE increased as PICO2 increased. At two-thirds and maximum workloads, VCO2 during exercise fell progressively with increasing PICO2. The ineffective CO2 removal is explained by the decreased alveolar-inspired CO2 gradient with increasing PICO2. Inadequate elimination of CO2 caused respiratory acidosis to be superimposed on the metabolic acidosis normally present during exercise.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1968
- Accession Number
- AD0685271
Entities
People
- B. E. Welch
- Richard D. Sinclair
- Stuart J. Menn
Organizations
- United States Air Force School of Aerospace Medicine