Plus, I had always heard that it was dangerous for a pregnant woman to let her heart rate get too high during exercise. I had no way to monitor my heart rate then except to stop and take my pulse, and that just was not convenient, or accurate, for that matter. I figured I would walk at a leisurely pace and that should be okay. Now, looking back, I wish that I had had a heart rate monitor then. It would have made exercising a lot easier and would have made me feel much more comfortable being able to constantly monitor my heart rate while exercising.
During and after my second pregnancy, I was determined to stay in shape and then to get back into shape as quickly as possible afterwards. Once again, I was worried about whether I was overdoing it and getting my heart rate up too high. I read numerous articles on the subject and was told by my obstetrician to keep my heart rate fairly low with no high intensity. The prevailing advice was to not let your heart rate go above 140 beats per minute when working out. That is when I knew that my Polar heart rate monitor would be an invaluable tool to be able to check my heart rate at all times and play it safe.
I soon found out, though, that keeping my heart rate at 140 bpm (beats per minute) or below would mean jogging so slowly that a fairly fast walker could keep up with me, and it was just not any fun. Plus, I began wondering about this 140 bpm rule of thumb. How could this apply to everyone? Women come in different sizes, shapes, ages, and levels of fitness. How could this number work for everyone? I read many articles about women running throughout their entire pregnancies, some of them even running marathons. They all had healthy babies but said they ran comfortably. I believe "comfortably" is the proper rule of thumb rather than a specific number.
I decided I would find what my comfortable heart rate zone would be. For me, it was between 150 and 160 bpm. I could still carry on a conversation and did not feel overly fatigued or exhausted during or after my runs. I chose to not run high mileage or tackle a marathon while pregnant. I ran 3-5 miles per day about five days per week. I did great with this. I always wore my heart rate monitor and kept my heart rate within my comfortable range. It made me feel safe and secure, and knew I was doing something healthy for my baby. I was getting a workout, but not overdoing it.
About half way into my pregnancy my belly and weight became too much for me to enjoy running anymore, so I decided to start walking with my heart rate monitor. I would walk fast enough to get my heart rate to between 130 and 140 bpm. If I walked up a hill I could even get it up to 150. Some women choose to run throughout their entire pregnancy, and that is great. For me, it just was not fun anymore and I run because it should be enjoyable. I really enjoyed the walking and I am sure my joints did also.
What I discovered is that there is no one magic number that fits all women for a safe maximum heart rate while working out when pregnant. There are many numbers and one of them will be just right for each individual. You have to get out there and experiment to find out what your special heart rate number is. The best way to do this is with a Polar heart rate monitor. I find it impossible to do it the old fashioned way - stopping and counting your heartbeat for ten seconds and multiplying by six. You would have to stop frequently and it is not accurate like a heart rate monitor is because every time that you stop and then try to get an accurate pulse, your heart rate has already fallen. A heart rate monitor displays your heart rate continuously so that you know your heart rate for the entire workout. Mine even tells me what my average heart rate is for the entire workout, which gives you more peace of mind.
So, all of you pregnant women who want to continue exercising, whether it be running, walking, cycling, swimming, aerobics or whatever else, strap on a heart rate monitor and workout at a comfortable pace. You should never get out of breath or feel exhausted. Find your comfortable zone and stick with it. Your zone will probably change as you get further along in your pregnancy. And never, ever engage in any form of physical activity without the express permission of your doctor.
Best of luck, and remember, keeping yourself healthy also keeps your baby healthy. That is what we all want, a healthy, beautiful baby!