How Will I Feel While Exercising During Pregnancy?
Pregnant women often notice that they feel out of breath more quickly than they used to. You may assume this is a sign that you're out of shape. In fact, during pregnancy you're breathing 20 to 25 percent more air because you need to get rid of the carbon dioxide levels in your own blood -- and in your baby's. (Babies in utero aren't breathing on their own, but they're still producing carbon dioxide, which transfers to the mother's blood. She needs to breathe more so she can get rid of it.) "So breathing more doesn't mean you're any less fit," explains Dennis Jensen, PhD, lead researcher on a Queen's University study of exercise and respiratory discomfort during pregnancy. It simply means that your body is adapting exactly as it should.
Jensen's research found that when pregnant women exercised to fatigue on a stationary bike at 20, 28, and 36 weeks, their maximal aerobic capacity (how hard they could work) was well preserved, even though they were breathing more.