Q: What constitutes an appropriate aerobic exercise prescription for a pregnant woman?
A: The Amercian College of Obstetricians and Gynecologists (ACOG) has established guidelines for aerobic exercise during pregnancy and the postpartum period. These advisory instructions are intended to be suitable for all pregnant women regardless of their basic level of physical fitness.
Many leading authorities, however, believe that the ACOG guidelines are too conservative and that a more appropriate exercise prescription for a pregnant woman would be one that is more individualized. These experts feel that decisions related to the type, intensity, duration, and frequency of exercise should be made according to a women's current fitness level, the stage of her pregnancy, and her personal interests.
It appears that some exercise activities are more suitable than others for a pregnant woman who is just beginning an exercise program. The most suitable aerobic exercises for the newly exercising pregnant woman are low-impact activities such as walking, swimming, cycling, and independent-action stair climbing.
Women accustomed to running prior to pregnancy can safely continue to do so provided they "listen to their bodies." All factors considered, the most appropriate form of aerobic exercise for a pregnant woman is the one that she most enjoys and can safely perform.
The fundamental purpose of exercise during pregnancy is to maintain or improve fitness. Thus, the intensity, frequency, and duration at which exercise is prescribed for a pregnant woman should be adjusted downward.
An appropriate level of exercise intensity for a pregnant woman is 50 percent of maximal oxygen uptake, or resting heart rate plus 50-60 percent of the difference between resting and maximal heart rate.
If, however, a pregnant woman is unable to comfortably carry on a conversation while exercising (a.k.a. the "talk test"), she should reduce her exercise work rate. The "talk test" tends to err on the side of conservatism and can be very helpful in ensuring that the intensity of an exercise bout is not excessive for a particular individual at a particular moment in time.
As far as exercise frequency and duration are concerned, it is suggested that a healthy pregnant woman exercise at least three times per week (non-consecutive days) for 20-30 minutes per session. Some examples (e.g., Joan Benoit Samuelson) exist of women who are able to engage in more intense, more frequent, and longer bouts of exercise. It is the opinion of many experts that an individualized exercise prescription is safer and more effective for the vast majority of pregnant women.
Over the course of their pregnancies, most women appear to spontaneously adjust the intensity, duration, and/or frequency of their workouts to appropriate levels (e.g., most women tend to naturally exercise at lower intensities and for shorter durations during the latter stages of pregnancy).
A good indicator of an appropriate exercise prescription is that a pregnant woman should be fully recovered within 15-20 minutes after the workout.
Source: Bryant, Cedric X. 101 Frequently Asked Questions about "Health & Fitness" and "Nutrition & Weight Control". Sagamore Publishing, 1999.
Sign up for ACE's FREE e-newsletter for fitness enthusiasts.