title: Effects of human pregnancy and aerobic conditioning on alveolar gas exchange during exercise.
abstract: This study examined the effects of aerobic conditioning during the second and third trimesters of human pregnancy on ventilatory responses to graded cycling. Previously sedentary pregnant women were assigned randomly to an exercise group (n = 14) or a nonexercising control group (n = 14). Data were collected at 15-17 weeks, 25-27 weeks and 34-36 weeks of pregnancy. Testing involved 20 W.min-1 increases in work rate to a heart rate of 170 beats.min-1 and (or) volitional fatigue. Breath-by-breath ventilatory and alveolar gas exchange measurements were compared at rest, a standard submaximal .VO2 and peak exercise. Within both groups, resting .V(E), .V(A), and V(T)/T(I) increased significantly with advancing gestation. Peak work rate, O2 pulse (.VO2/HR), .V(E), .V(A) respiratory rate, V(T)/T(I), .VO2, .VCO2, and the ventilatory threshold (T(vent)) were increased after physical conditioning. Chronic maternal exercise has no significant effect on pregnancy-induced changes in ventilation and (or) alveolar gas exchange at rest or during standard submaximal exercise. Training-induced increases in T(vent) and peak oxygen pulse support the efficacy of prenatal fitness programs to improve maternal work capacity.
authors.affiliation: School of Physical and Health Education, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Sonja E
authors.initials: SE
authors.lastname: McAuley
authors.forename: Dennis
authors.initials: D
authors.lastname: Jensen
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McGrath
authors.forename: Larry A
authors.initials: LA
authors.lastname: Wolfe
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D010101:Oxygen Consumption / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D011247:Pregnancy / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D015656:Respiratory Mechanics / Q000502:physiology