Note: It's important for those who are pregnant and engaged in an exercise regimen to seek the advice of their physician and be evaluated prior to initiating any exercise program.
Pregnancy is the gift of life, but it can also feel like a temporary setback for women who run.
We got a few words from Dr. Robert Stewart, assistant professor of obstetrics and gynecology at UT Southwestern Medical Center in Dallas, to give you an idea of how to stay active during your nine months of pregnancy.
Active: What is the general consensus about running while pregnant, and how has it changed over the years?
Dr. Stewart: Previously, the American College of Obstetrics and Gynecology recommended that women keep their heart rate less than 140 beats per minute. And many obstetricians previously would advise pregnant women to follow this or even to reduce the amount of exercise. However, in 1994, this restriction was removed, and generally, exercising in pregnancy is now seen as a good thing.
Currently, it is recommended by the U.S. Department of Health (the Physical Activity Guidelines for Americans in 2008) that healthy women who become pregnant (non-exercisers and moderate exercisers) should begin or continue moderate intensity aerobic activity during pregnancy, accumulating at least 150 minutes a week. ACOG states that women with a low-risk pregnancy can participate in moderate physical activity for more than 30 minutes a day. More vigorous activity is generally regarded as safe for women who are well trained before pregnancy.
Vigorous exercise has not been well studied in pregnancy, so women who have not previously been involved in vigorous exercise should not begin this while pregnant. Those already involved in vigorous exercise may continue, provided they remain healthy. It is recommended that women who participate in vigorous or strenuous activity should receive close medical supervision. Moderate activity is defined as 40 to 59 percent of heart rate reserve; and vigorous exercise is generally defined as 60 to 84 percent heart rate reserve; and exercise over this intensity is not specifically addressed in current research.
Active: What are the benefits of running while pregnant?
Dr. Stewart: Women continue to receive the benefits from exercise that they did prior to pregnancy while they continue to exercise in pregnancy. In addition, women who exercise in pregnancy have improved cardiovascular function, improved strength and improved sense of well being, and the American Diabetes Association endorses it as "a healthy adjunct therapy" for gestational diabetes that is not controlled by diet alone. Women who exercise also tend to have improved body image and improved psychological well-being.
Active: After finding out she's pregnant, should a woman keep running her normal miles?
Dr. Stewart: This goes back to the definition of moderate vs. vigorous exercise, as most of this information we know about this comes from those definitions, where vigorous is 60 to 84 percent heart rate reserve. In general, if a woman is engaged in a running program that is of moderate intensity, she can continue this without concern (assuming a normal healthy pregnancy).
If, however, she is involved in a vigorous training program, as some high-intensity athletes, it is difficult to counsel pregnant women on the advisability of continuing at this intensity. If they have previously been involved in a vigorous program, ACOG states that they may continue that vigorous program.
There is some evidence that women can exercise beyond a threshold at which fetal well-being can be compromised, and some research suggests that this is at or above 90 percent of maximum effort. If a woman is a competitive athlete, she tends to maintain a more strenuous schedule longer into the pregnancy and returns to more strenuous training sooner; however, she should have close obstetric supervision.