High-Impact Exercise in Pregnancy: Risks & Recommendations

Question
QUESTION: Dear Helene,

I've read everywhere that high-impact exercise is not recommended after a certain point during pregnancy (maybe from second trimester on). I was wondering if you could explain to me exactly *why* it is not recommended. I do know about the overheating issue, which is something that can be monitored with a (rectal) thermometer. But other than that, is there any reason not to continue with high impact, including plyomterics and jumping jacks, if my body still feels okay with it? I'm starting my 27th week.

Thanks a lot!


ANSWER: Pregnancy hormones relax and lengthen connective tissues, including ligaments, which hold joints in proper alignment. This increases the likelihood of injury, especially with high-impact activities. In addition, the postural changes associated with the last half of pregnancy decreases balance and proprioreception (awareness of where the body is in space) and this too leaves pregnant women more vulnerable to injury too.

But if you are well-trained, athletic, and have been doing various types of plyometric exercises before you became pregnant, you might be able to continue to do them safely until the third trimester.

At this point, you'll find that the size of your belly will make you a lot less agile, and/or the jarring forces on you belly will be uncomfortable. If at any point in your training you experience discomfort, or a decrease in technical ability, stop doing that exercise.

If you haven't already started doing isometric core exercises, start now. Focus on strength in your Transverse Abdmoninis (TvA), as strength here helps to prevent back pain, instability, and diastasis recti. The TvA is also the main expulsion muscle, and so greatly aids in labor and delivery.

Two safe TvA exercises for pregnancy can be found at the bottom of page:
http://www.befitmom.com/strength_training.html


---------- FOLLOW-UP ----------

QUESTION: Thank you, Helene. Just two follow-up questions:

1. You mentioned that if I am well-trained and athletic, I can continue my high-impact workout until the third trimester. Does this mean until the beginning of the third trimester (week 28) or throughout my third trimester? (Is there any reason why I cannot continue throughout, making adjustments if necessary?)

2. A few years ago, I had a die-hard kickboxing instructor continue teaching and participating though her ninth month. However, I noticed that she would avoid jumping or hopping. Is the jumping/hopping/jarring forces on their own bad for the baby or is it simply uncomfortable for the mother due to the large size of her belly.

Thanks again!


Answer
To your first Q: when and how you make the appropriate modifications really depends on you, and what feels right/safe.

I didn't get in to this in my first answer, but another issue that your body has to deal with is the learning of new and slightly different neuromuscular patterns. So not only are your joints looser and less stable, but as you belly expands and changes you center of gravity, you need to be adapting all the time. So in a way, all of your neuromuscular patterns are new, not drastically different, but still new.

Additionally, the shift in your center of gravity combined with the increased body weight near that center means that it takes longer to shift and move your body. So especially in something like kick-boxing, simply putting your foot down, shifting your body weight to that leg and possibly changing your orientation in space is much more work for your body to do efficiently. As you can see, one incomplete shift of gravity, or incomplete body orientation would be enough to cause a sprained ankle, or twisted knee.

Q 2: Jarring is not so much of an issue for the baby, as the amniotic fluid greatly reduces/eliminates those types of forces, here again the issues are joint instability, neuromuscular and balance challenges. But many women do feel jarring forces in their bellies adn sometimes lower backs, which is really uncomfortable, and this is due to the laxity in the uterine ligaments, which keep the uterus in proper alignment as pregnancy progresses.