Heart Rate During Exercise & Pregnancy

Exercise during pregnancy is a beneficial part of your prenatal care. As long as there are no major complications, exercising on a regular basis will help prepare your body for labor as well as for getting back in shape after childbirth. One major concern for many expectant mothers is the intensity at which they should exercise, to keep their heart rates at a safe level. Today, with many women athletes and fitness enthusiasts exercising during pregnancy, much more research has gone into the study of this important issue.

Guideline History

Concerns about heart rate, pregnancy and exercise have been debated since the first exercise and pregnancy guidelines were published by the American Congress of Obstetricians and Gynecologists (ACOG) in 1985. The guidelines were vague, and there was very little scientific evidence backing the advice. Mothers were strongly encouraged not to engage in any activity that would cause their heart rates to succeed 140 beats per minute, which excluded any vigorous activities such as running and many aerobics classes.

Today

Twenty-five years later, the ACOG has much more specific guidelines. The heart rate restriction (140 bpm) has been removed, and women are encouraged to limit their exercise activities using their own instincts and the help of their healthcare providers. Many women who were very active previously to becoming pregnant are given the okay to continue participating in their activities. Contraindications are encountered in the natural progression of pregnancy. Many women are encouraged to stop any overly vigorous activities once they reach their second and third trimesters. Activities such as contact sports or activities that include a high risk of falling should be avoided.

Intensity

As you carry more weight, your body works harder to maintain an inner equilibrium. This is an important concept to remember as your baby grows. As a woman progresses to her second and third trimesters and her weight gain increases, temperature regulation may become a concern. Pregnant women should make sure to not overdo it and to listen to their bodies. Since every woman's physical limits are going to be different, using a generalized intensity range for the heart rate would not be appropriate. The American College of Sports Medicine (ACSM) recommends that pregnant women should use the scale of perceived exertion (RPE) rather than heart rate. This allows an individual to listen to her body, depending on her fitness level.

Use of RPE Scale

Your rate of perceived exertion or (RPE) is a much better indicator of how hard you are working during exercise, versus using heart rate alone. The scale starts at 6 (zero intensity) and goes to 20 (maximum intensity). During pregnancy women should keep their intensity at 11 to 13, or a fairly light to moderate intensity level on the RPE scale. Due to the differences in body types, this will allow beginners and advanced athletes to all meet fitness goals during pregnancy.

Considerations

Pregnancy puts a large amount of stress on the body from the changes that take place. Changes in hormones, weight and joint stability can make certain fitness activities uncomfortable. Implementing cross training routines and non-weight bearing activities such as swimming and cycling can be very beneficial. Pregnancy also requires an additional 300 calories per day, so make sure that you are eating a healthful balanced diet and that you are meeting your caloric needs for pregnancy as well as your physical activiy needs.