I am 15 weeks pregnant and have noticed that my heart rate while exercising seems to be a lot higher now than before I was pregnant. I didn’t wear a heart rate monitor before I got pregnant but have started using one since I am not supposed to get my heart rate too high. Now when I go for a run (jog) even a very easy pace has my heart rate at 145-150. I would guess beforehand I was more in the 125-130 range. I can not run up the slightest incline even at a snails pace without my heartrate going above 155.
All the literature (and there is not much and it’s not based on any studies) recommends keeping your heart rate below 140 when exercising during pregnancy. At my last OB appointment my doctor said not to worry about the 140 number so I have set a very arbitrary limit of 155 for myself. I figure this is high enough that I can lightly jog but not to high that it will harm my little one.
Wondering if any of the ladies (or guys wives/gf’s) have had similar experiences.
My wife went thru a similar experiance and we also talked to her OBGYN about excercise and we were lucky enough to have a fellow runner practicing as a nurse practitioner in the same office as our OBGYN.
That doesn’t make me a doctor so you’d probably want to verify all of the following with him.
The higher HR is caused by an increase in blood volume and fluids. Not sure exactly how it works but the way it was explained to me is that the heart has to work harder becaue it has to move more fluid and support more tissue etc. My wife seemed to cycle. Some times the HR would go very high other times it would seem to level off. If memory serves she went thru this cycel 3 or 4 times, although she was only able to run up until 5-6 months or so, doctors orders.
The HR limit of 140 is kinda like the Max HR calculation of 220-AGE. It’s a “starting point”. Our doc said you just don’t want to “Stress” the baby. Keep the effort levels low, no high intensity stuff. Beware of overheating and Hydrate, hydrate, hydrate. Obviously the “effort level” is going to be very personalized. I’m sure Lori Bowden is doing much more strenous excercise during her pregnancy than my wife did.
MJ-
Everything you’re experiencing is VERY normal… When pregnant with my now 3 year old daughter, I was affected the same way. You’re doing the right thing-- just go at a comfortable pace and you’ll be good. The 140 rate is outdated and not even in the ACOG (American Council of Obstetrics and Gynecology) guidelines anymore. Here is a link to an article I wrote after delivering my daughter-- all on exercising while p/g. Also, think about picking up the book called “Excericising Through Your Pregnancy” by James Clapp. It’s a GREAT resource.
ACOG guidelines were always a limit of 140, but I believe they went away from that in the 2002 position paper. (Sorry, I don’t have the literature in front of me.) As you indicate, these numbers are/were very conservative, mostly because controlled studies on pregnant subject are potentially unsafe (“OK Mrs. Jones - we’re going to have you train above what we think is safe to see if you damage the fetus”). Keep in mind that you will have a higher resting heart rate than before, and your exercise heart rate will also be higher for a given activity than it was before. As long as you have no contraindications to exercise, you should be fine using Rating of Perceive Exertion rather than HR. Remember that your hydration and caloric requirements are higher than before and because extended workouts tend to raise your core body temparature, you should be careful in hot conditions and may need to shorten the duration of some workouts. You may also need to avoid exercises in the supine position (things like crunches) now that you’re in your second trimester because it will decrease your cardiac output.