Common Myths About Exercise During Pregnancy
You’ve likely heard some, if not all, of the statements below regarding physical activity during pregnancy. Let’s dive into why some of these are outdated and how to instead, approach exercise with confidence.
MYTH #1
Heart rate should not exceed 140 bpm.
The 140 bpm limit was originally recommended by ACOG in 1985 and then removed from guidelines in 1994. Despite many studies indicating otherwise, we still hear about it today.
The main issue that makes heart rate not a reliable way to measure intensity is because there are so many variables that can affect it. First, we have to consider the changes that happen to your resting heart rate during pregnancy. It can increase dramatically so the difference between an elevated resting heart rate (RHR) and 140 bpm can be quite minimal.
The other important aspect heart rate does not take into consideration is the individual’s personal fitness level. Seasoned athletes will have different heart rate responses compared to those that don’t exercise regularly so blanket values like 140 bpm simply don’t make sense here.
Research since then has shown that in healthy pregnancies, exercising up to at least 80% of max effort does not result in fetal distress, slow fetal heart rate or inflict harm on the baby. In fact, being active reduces pregnancy complications. There are currently more and more studies being conducted to help us learn more about exercising >80% intensity especially as more elite level athletes become moms.
Instead of HR values, you can measure intensity of exercise by using rate of perceived exertion (RPE) or the talk test and aim for exercising at a moderate intensity. See below to get more info on what this looks like:
RPE
During resistance training, using rate of perceived exertion (RPE) can be helpful to gauge your effort levels.
Low Intensity: 50-60% intensity or 5-6/10 on RPE scale; able to easily do all repetitions without any struggle. Your form is near perfect with every single repetition. After completing your set, you feel you could do several more reps without issue.
⭐️ Moderate Intensity: 70-80% or 7-8/10 on RPE scale; able to do all repetitions but last few repetitions are more challenging. After completing the set, you feel you could do maybe 2-3 more reps. This is the intensity we are aiming for.
High Intensity: 80-100% or 8-10/10 on RPE scale; difficult to do all the repetitions and may require a spot in order to help with the last 1-2 reps. You used all you had in the tank to complete the reps.
The Talk Test
ACOG recommends using the Talk Test as another way to gauge effort levels. This is a helpful tool when performing more cardio-based exercise like running, walking, biking or machines. You are evaluating how easy it is to speak or pause to catch your breath during the exercise. The longer you can speak without needing a break, the lower the intensity of the exercise.
Low Intensity: Able to speak easily without needing to take a break from talking
⭐️ Moderate Intensity: Able to speak about a sentence before needing to pause to take a break from talking. This is the intensity we are aiming for.
High Intensity: Only able to speak a few words before feeling winded or needing to take a break from talking
MYTH #2
Avoid rotation during pregnancy.
This stems from the thought that rotation compresses the uterus and would stress the baby. The uterus is more resilient than that, not to mention all of the supporting tissues around it.
In fact, the opposite is true – we absolutely need rotation during pregnancy! Rotation through the trunk, pelvis, and hips is imperative for normal movement: walking, running, stair climbing, and most activities during our day. Limiting this rotation can contribute to upper and lower back pain, hip, and pelvic pain. It can lead to pelvic floor dysfunction including pelvic floor tightness, constipation, tailbone pain, and more.
It is also imperative for birth prep purposes. We use rotation of the hips and pelvis to promote opening in different areas of the pelvis so that the baby has an easier time descending (especially in the lower half of the pelvis).
Definitely keep rotation as an emphasis in your training programs!
MYTH #3
Avoid core strengthening exercises during pregnancy.
The core muscles go through an extreme amount of change during pregnancy, the main one being that they function on a significant stretch. Muscles become more inefficient when they operate from a lengthened position, so it is important to continue to strengthen them! Not only does this help provide support during pregnancy to the trunk and pelvis, but also aids in postpartum recovery and diastasis recti rehabilitation.
You will likely have to modify and scale your typical core routine as you progress through pregnancy. But that doesn’t mean we remove them entirely. Some great go-to movements that are common in the third trimester include pallof press, incline plank, side plank variations, resisted trunk rotations, and more.
MYTH #4
Avoid exercising on your back during pregnancy.
Lying on your back, especially in the first half of pregnancy, is usually very well tolerated. The concern with this is that lying on your back causes the uterus to compress on major blood vessels, potentially decreasing blood supply to the baby. Physiologically, this is something to consider, but more so during later stages of pregnancy when the uterus is bigger. In these later stages, it is still safe to do short bouts of supine exercise (think 2-3 minutes) before changing positions. But if you feel symptoms like light-headedness, nausea, dizziness, or feeling unwell, it is recommended to switch it up. It may be preferred to swap to incline or standing positions when applicable. I love using my incline bench for supine exercises like bench press, chest flys, skullcrushers and lat pullovers. It feels a lot better on my belly and low back in the last part of the third trimester. You will know when you need to make this switch.
We want our moms-to-be to prioritize movement and physical activity with confidence! It is absolutely important to consider how things may need to shift during pregnancy, but we are learning more and more as research progresses. If you need help with your prenatal programming, be sure to check out my program Generating Resilience in Pregnancy to have it all laid out for you from weeks 4-41!
