Is it safe to do isometrics during pregnancy?

I got a great new question from one of my Pregger Fit program users. She wondered about safety of useing isometric exercises during pregnancy.

Isometrics are exercises where you contract muscles without movement. For example a wall squat, carrying grocery bags, the plank abdominal exercise, etc. Imagine making force with your muscles without moving a particular joint.

Yes, isometric contractions increase blood pressure and this is where the original "ban" came from. However, ANY exercise increases blood pressure and it needs to! Otherwise the body can't function to pump more blood to the heart and the working muscles. :)

This only becomes a problem for women with preeclampsia (pregnancy induced hypertension) because their blood pressure is already too high. Also, it would be a problem if the blood pressure didn't come back down to normal after exercise. (In that case any exercise would be problematic, including sex!) The studies done on pregnant women and isometrics demonstrated that blood pressure returned to normal after the exercises.

There was another study done on women in advanced pregnancy that demonstrated that yes, blood pressure and heart rate go up during isometric exercise, yet there was no change in placental circulation.

One action that can cause problems is the valsalva maneuver. This is when you hold your breath during exercise. This is contra indicated for everyone, not just preggers, as it increases blood pressure on top of the normal exercise induced increase that is needed. Often isometrics get accidentally done while holding your breath. That would be a no-no.

In our daily life we do isometrics every day at varying intensities. With babies our poor biceps do marathons of isometrics as the little one decides to finally fall asleep in our arms and will ONLY sleep there and in one position and we are stuck holding our biceps tight for hours. :) Another example of a beneficial isometric is a constant activation of the core and pelvic floor. This is one of the best ways to prevent problems in that area. Our postural muscles also work isometrically all day long keeping us upright and elegant.

The question was more specific to a wallsit with an arm slide. This exercise is safe to do assuming you stay within the general pregnancy exercise intensity guidelines. Exercise when pregnant should be done at a "comfortable" level. For example in this exercise, you should feel challenged yet when you finish a set, you should feel like you could have done it a bit longer. So whether an isometric squat or a "regular, moving" squat, you should at most be in a "somewhat hard" category on the intensity chart. And just like during any exercise, keep breathing to avoid an exaggerated increase in blood pressure.

Here are links to a couple of studies about pregnancy and isometrics:

http://www.ncbi.nlm.nih.gov/pubmed/8238141

http://www3.interscience.wiley.com/journal/102520398/abstract