Does Relaxin Increase Risk of Injury in Deep Squats?
In countless websites and articles about exercising during pregnancy, you will commonly read that women should not squat below parallel (in which the knees are at a 90 degree angle) during pregnancy due to the loosening effects of the relaxin hormone on joints and ligaments during pregnancy. I have always been skeptical of this claim for a number of reasons. For one, if squatting below parallel is really that unsafe for pregnant women, why is this not included in the ACOG (American College of Obstetricians and Gynecologists) recommendations? Two, squats are usually performed in a controlled manner; they are not a ballistic movement so therefore the risk of twists and strains should be the same or less than just going through your day-today activities. And finally, and more importantly, squatting to parallel actually places the knee ligaments in their least stable position. On the other hand, squatting to less than parallel (higher) doesn’t allow for full recruitment of the glutes and hamstrings which can lead to injuries due to muscular imbalance because the quads are disproportionately stronger than the glutes and hamstrings.
Benefits of Deep Squats
The same reasons that I tell my non-pregnant athletes to support squatting below parallel apply to pregnant women as well…the basic principles of human anatomy do not change just because a woman is pregnant. The quadriceps muscle attaches to the tibia (the shin) just below the kneecap. When the quads pull on the knee, the force is directed forward relative to the knee joint. When the hamstrings are positioned correctly in the squat with the hips moving back and torso leaning slightly forward, the backward pull of the hamstrings balances the forward pull of the quads. The balance is optimal when the hips are below parallel. In addition, when squats are performed in this fashion they help strengthen much more than the legs. Squats work the muscles of the back, the abdominal muscles, and help protect the knees and spine.
Relaxin Risk Theoretical
In addition to the benefits of muscular balance and strengthening of the musculature that surrounds and supports the joints, “the relaxin risk is largely theoretical,” says Patrick O’Connor, Ph.D. co-author of a a 2011 University of Georgia study which found that a low-to-moderate-intensity strength program is safe for pregnant women, even for beginners. The 12 week study followed 32 women who were 21-25 weeks pregnant when the study began. The women worked out twice a week increasing their weights lifted by an average of 36% over the course of the study. Not one woman got injured. Although this was a small study and the research on resistance/weight-training during pregnancy is limited, the currently available research supports resistance training as a safe and effective type of exercise to perform during pregnancy.
Potential Risks of Deep Squats
Of course the safety of an exercise or exercise program is dependent on a number of additional factors, namely form. In a 2008 article (Full Squat During Pregnancy – To Do or Not To Do) Jacqueline Gradish, BSc., a pre/post-natal exercise specialist, outlines one of the potential dangers of performing full squats:
“The majority of people have muscle imbalances and are unable to maintain neutral spine position. Performing a full squat with an imbalance can further pull your pelvis to one side and may exacerbate pelvic shearing forces in the pubis symphasis (front join of your pelvis) and put strain on your sacroiliac joint. As your pregnancy progresses, your pelvis is opening and widening from the front of your pubis symphasis. This makes more space and allows for your growing uterus to house the baby. This growth puts more strain on your pelvic floor muscles. As you squat to neutral where your knees are at 90 degrees to the floor, the pressure of your uterus increases on your pelvic floor muscles and your pelvis tilts anteriorly. If you squat lower, you are at risk of going into a compromising anterior pelvic tilt position due to the extra front load of your protruding belly and your relatively inefficient abdominal muscles. This can put undue strain on your back.”
Proper Technique = Safe Squats
However, the author later explains that the main limiting factor that may justify not squatting below parallel is lack of proper technique. The fact is that most women, especially in Western societies (in the Eastern hemisphere, especially Asian countries women and men spend a great deal more time in a squatting position in their daily lives) do not know how to squat correctly. But for healthy individuals without a known muscle imbalance and who have received proper training in squat technique, full squats are the best exercise for developing overall strength and fitness as well as for preparing for labor.
As always, you are the best judge of what is best for your body. Women who are experienced with squat technique can continue to squat to full depth provided they are reducing the load they are using. Good form is key to safety therefore women should reduce their weights to a load that allows them to maintain good technique. Women who are inexperienced with proper squat technique should consult a personal trainer, especially a prenatal/postnatal exercise specialist or someone experienced in training pregnant women, for help.