Adjust your workout to suit your pregnancy

Pregnancy and the initial months following the birth is an exciting time for women. However, there are a number of changes that occur in the body that can lead to women developing lower back and SIJ (sacroiliac joint pain) which can have long-term consequences. 

Women need to alter their pregnancy exercise routine to minimise the load through the pelvis. Pregnancy Pilates classes under the supervision of a qualified professional are ideal.

Studies have shown that if you were active prior to falling pregnant then you should continue to exercise but reduce the intensity by 25-30% (maximum heart rate should not exceed 140-150bpm). If you were previously inactive, then gradually increasing your exercise as the activity is good both for the mother to be and the baby in preventing conditions such as gestational diabetes.
There are a number of changes that occur in the body during pregnancy, including;

  • Your heart rate should increase by 15bpm as more blood is directed to the uterus, kidneys and digestive systems.
  • Your normal blood pressure should be around 140/90. Some women develop ‘supine hypotension’ after 4 months gestation where blood pressure may substantially reduce when you lie on your back due to the uterus compressing a major vein that returns blood to the heart – if you feel faint or breathless lying on your back turn onto your left side.
  • Normal weight gain is 10-12kg over the 9 months.
  • Hormone release (relaxin) causes laxity of ligaments throughout the body resulting in increased range of movement. This includes the Sacro-Iliac Joint (SIJ) which can cause considerable pain walking, getting in/out of the car, rolling over in bed or any activity that involves standing on one leg (eg putting on socks).  Occasionally women may feel the pain refer to the front of the pelvis at the Pubic Symphysis (PS).
  • The centre of gravity shifts forward causing reduced stability and sometimes a ‘waddling gait’.  The resulting increased curvature of the spine and forward tilt can cause some lower back pain and/or pelvic pain.
  • Some women experience something called “rectus diastasis” where the connective tissue of the  stomach muscles split in the midline as the baby grows and stretches the muscles.
  • The gluteal muscles and hamstrings tighten which may contribute to lower back and/or pelvic pain.

There are numerous benefits of exercising during pregnancy which include;

  • Strengthening the legs to help or prevent fluid retention, leg cramps and varicose veins.
  • Strengthening the lower back and deep abdominal muscles to help prevent or relieve lower back pain.
  • Minimise excessive maternal weight gain which can contribute to gestational diabetes.
  • Improved functional activation of the pelvic floor muscles.


Some pregnancy exercises should be modified. For example, if the woman has SIJ pain then she should avoid running or any single leg exercises as this places a greater shearing force through the joint.  After 20 weeks you should minimise the strong upper abdominal work such as plank holds and abdominal crunches as this places more load through the stretching rectus abdominals and may lead to a rectus diastasis. Other precautions include;

  • As the growing fetus cannot regulate its own body temperature (it is normally 1deg C higher than the mother’s temperature) heavy exercise that raises the mother’s temperature above 38.5deg for more than 20minutes should be avoided.
  • Avoid contact sport such as netball or basketball. Women should also not scuba-dive when pregnant as the fetus cannot adjust to the change in pressure.
  • If the mother has pre-existing cardiovascular disease or restricted lung disease then they should avoid exercise during pregnancy (gentle walking is usually acceptable, may need to monitor breathing rate and heart rate more closely).
  • If the woman has a low-lying placenta they should not exercise after 32 weeks.


Many of the physiological changes that are experienced during the pregnancy will continue through the post-natal period, therefore, some precautions are still necessary. After vaginal delivery, gentle daily exercise such as walking can begin. More intense exercise can begin 4-6 weeks after delivery, or when the bleeding stops, as exercise may increase blood loss.

Clients who have had a Caesarean delivery should not lift anything heavier than the weight of the baby for 6 weeks and should not do any strenuous exercise for 12 weeks post-partum. There is also a theoretical risk of lactic acid being transferred in breast milk, therefore, women should exercise after breastfeeding, not before.


So what is “the core”? The main muscle groups that provide stability to the lower back and pelvis are the Transversus Abdominals (TrA), Pelvic Floor Muscles (PFM) and Lumbar Multifidus (LM).

Transversus Abdominals are the deepest layer of abdominal muscles and spanning between the lower ribs and the top of the pelvis, running horizontally from the spine around the torso to attach to the fascia (linea alba) at the front. They function like a muscular corset to stabilise the lower back and pelvis. To activate TrA gently draw your lower abdominal wall (between belly button and pelvis) towards the spine, “imagine you’re zipping up a tight pair of jeans”.

Pelvic Floor Muscles are a group of muscles that span the base of the pelvis like a hammock and function to maintain urinary and fecal continence as well as support the pelvic posture. To activate the PFM imagine stopping the flow of urine which will cause the PFM to squeeze together and lift within the pelvis.

Lumbar Multifidus is small muscles that form an upside-down “V” spanning from the outer part of one vertebra to the central process of the vertebra above (sometimes 2 or 3 above) and work to stop the shearing forces between the spinal segments which can cause more load on the discs. To activate the LM think about sticking your tailbone out slightly (don’t allow the pelvis to tilt too far forward).