Effects of Pregnancy on Responses to Exercise Above and Below the Ventilatory Anaerobic THreshold
Abstract
This research contract examined the effects of healthy human pregnancy on cardiac autonomic function(Study #1), oxygen uptake kinetics (Study #2)and acid-base regulation (Study #3) at rest and during upright cycling at intensities above and below the ventilatory anaerobic threshold(T to the vent). Results from Study #1 support the hypothesis that cardiac vagal/parasympathetic modulation is reduced in the resting state and that sympathoadrenal modulation is blunted during strenuous exercise above T to the vent in late gestation. These findings have important implications for the use of heart rate to regulate exercise intensity during pregnancy. Study #2 is still in progress. Findings from Study #3 demonstrated that plasma H+ is lower at rest and during exercise in the pregnant vs. nonpregnant state. Exercise-induced increases in H+ were similar quantitatively in the pregnant vs. nonpregnant state, but pregnant subjects have lesser reductions in the strong ion difference (SID)and require less respiratory compensation. Findings also suggested that plasma osmolality and SID contribute, in addition to circulating progesterone, to pregnancy-induced increases in pulmonary ventilation at rest and during exercise. Maximal exercise tests conducted as part of Studies #1 and #3 confirmed that maximal aerobic power and work efficiency are well-preserved in healthy physically active pregnant women and that such tests involve minimal changes in fetal heart rate.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1999
- Accession Number
- ADA384354
Entities
People
- Larry A. Wolfe
Organizations
- Queen's University