Running During Pregnancy: Heart Rate & Safety Concerns

Question
I am currently 5 months pregnant (42 yrs old) and have been running regularly since January of this year. My doctor said to use a heart monitor and keep my heart rate at 140. I used it for the first time and within the first 5 minutes my heart rate is up to 140. I don't feel like I have been exerting myself. Do I need to stop running? When should I be worried?

Answer
In 2002, ACOG, the American College of Obstetricians and Gynecologists revised their restrictions on exercise HR for pregnant women.

The original study, on which the HR restriction of 140 BPM were based, was rudimentary at best. After larger, better designed studies were completed, the ban was lifted.

ACOG now recommends that pregnant women rely on perceived exertion while performing aerobic exercise. If you stay in a zone that you feel is "somewhat difficult" then you will be in the middle of your aerobic training zone.

Pregnant women should not work out beyond then aerobic capacity (cross their anaerobic threshold). At this point you will begin to pant and can not speak naturally.

Since you are in very good aerobic condition, I suggest that you use a combination of perceived exertion and your HR monitor. After your initial warm up period, when you feel that you are in the "somewhat difficult" zone, take you HR. This will give you an accurate baseline to which to work off of.

As your pregnancy progresses, and your baby gets larger, her need for oxygen will rise, and accordingly, your rate of perceived exertion for any given workout will too. You'll find that in order to stay in a good aerobic zone, that you'll need to slowly decrease the intensity of your workouts. Keeping track of both your perceived exertion in correlation to your HR will allow you to run safely and maintain a high fitness level throughout your pregnancy.

Some women find that as their bellies get big, that the impact of running places too much stress on the uterine ligaments. You don't want you belly to be bouncing along with each stride. If this happen to you, switch to fitness walking, or another non-impact activity like swimming, elliptical trainer, or stationary bike.

For more information on cardiovascular exercise during pregnancy go to http://befitmom.com/aerobic_exercise.html