title: Cardiorespiratory fitness in highly active versus inactive paraplegics.
abstract: Maximum and submaximum arm crank exercise performances were assessed in male paraplegics (PARA) with the purpose of comparing cardiovascular responses among individuals of highly active (A, N = 15) vs inactive (I, N = 15) lifestyles. The A PARAs (average VO2 peak during arm cranking 2.24 l.min-1) demonstrated a significantly higher maximal cardiorespiratory fitness compared to I subjects (average VO2 peak 1.56 l.min-1). During graded arm exertion, at exercise intensities approximating 45%, 57%, and 70% of VO2 peak, the active subjects developed cardiac outputs (assessed via CO2-rebreathing) ranging from 9.07 to 11.21 l.min-1; a 34-44% advantage relative to their inactive counterparts (6.30-8.36 l.min-1). Similarly, exercise stroke volumes for A (76-80 ml) were 38-45% higher than for I paraplegics (55-56 ml). Although both groups demonstrated a distinctive circulatory hypokinesis during arm cranking, the immediate pattern of cardiovascular response was dissimilar for the highly active versus inactive subjects. The former demonstrated a predominantly "central" adaptation to steady-state arm exercise (exhibiting normal stroke volumes and arteriovenous O2 extractions for spinal cord-injured subjects), while the latter displayed markedly reduced stroke volumes concomitant with abnormally large peripheral arteriovenous oxygen extractions for a given oxygen uptake.
authors.affiliation: Department of Health, Physical Education and Recreation, University of North Texas, Denton 76203-3857.
authors.forename: G M
authors.initials: GM
authors.lastname: Davis
authors.forename: R J
authors.initials: RJ
authors.lastname: Shephard
mesh_terms: D000293:Adolescent; D000328:Adult; D002302:Cardiac Output; D003430:Cross-Sectional Studies; D015444:Exercise; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D008168:Lung / Q000502:physiology*; D008297:Male; D010101:Oxygen Consumption; D010264:Paraplegia / Q000503:physiopathology*; D010809:Physical Fitness; D013990:Tidal Volume