For years pregnant women were viewed as needing to be confined to rest for their entire pregnancy to avoid complications. However, only up until recently, 2002 in fact, the American College of Obstetricians and Gynaecologist (AGOG) published new recommendations regarding the benefits of exercise during pregnancy and stipulated specific guidelines regarding exercise prescription and contraindications (both absolute and relative) to exercise. Pregnancy is a unique time where a woman will undergo many physiological, physical and behavioural changes in order to prepare her for nourishing and nurturing her child. All systems, including but not limited to the cardiovascular system, metabolic system, respiratory system, musculoskeletal system and endocrine system, within the woman’s body are altered in order to provide for the baby.
A woman will experience cardiovascular adaptations such as an increase in blood volume, heart rate, stroke volume (and ultimately cardiac output), as well as, a decrease in systemic vascular resistance to establish a circulatory reserve that is necessary to provide nutrients and oxygen to both the mother and baby. Metabolically, a woman’s nutritional needs increase by approximately 300 cal/day, which there increases her basal metabolic rate and subsequently heat production. This ultimately leads to a change in thermoregulation. Pregnancy is also associated with profound respiratory changes, including an increase in minute ventilation, which increases arterial oxygen tension, resting oxygen uptake and consumption. Musculoskeletal adaptations included weight gain, which therefore increase the force and pressure through a women’s joints, ligamentous laxity as a result of an increase in the hormone relaxin, lumbar lordosis and subsequently low back pain, and changes in balance as a result of the change in centre of gravity. As well as this, rectus abdominus begins to move apart (still connected through connective tissue) to make room for bub. This leads to the weakening of the abdominal wall.
So how do all of these changes affect exercise?
- Avoid raising body temperature too high – for example, reduce exercise level on hot or humid days, or move inside.
- Avoid Valsalva manoeuvre (breath holding), such as lowering weights and increasing repetition ranges.
- Avoiding supine position (lying on your back) after 26 weeks – there are multiple other ways you can perform an exercise that may traditionally be performed on your back.
- Include appropriate abdominal wall exercises – NO crunches or planks – to help reduce diastasis recti.
- Understand that training goals are adjusted in pregnancy to optimise pregnancy health, delivery and recovery – it’s not a time for peak performance.
- In addition, if you develop illness, injury or complication of pregnancy, talk with your doctor, midwife or Accredited Exercise Physiologist before continuing or restarting your exercise program.
For women without contraindications to physical activity, exercise is safe for both the woman and developing foetus. Although there is no conclusive evidence that exercise effectively prevents gestational diabetes mellitus, preeclampsia, or perinatal depression, most studies have a positive correlation between exercise and reducing the risk of the former conditions. Studies have concluded that exercise during pregnancy does appear to have beneficial effects on reducing glucose levels, the risk of caesarean section or instrumental vaginal deliveries, and maternal weight gain. As well as this, women also experience increased energy and fitness, a reduction in back and pelvic pain as a result of improved posture, improved sleep and management of insomnia, stress relief and an increased ability to cope with the physical demands of motherhood. In general, women who are physically active prior to pregnancy should be advised to maintain their level of activity if desired, while physically inactive women should be encouraged to begin exercising.
A pregnant woman with no absolute or relative contraindications to exercise (refer to AGOG guidelines) should be advised to:
- Perform at least 30 minutes of moderate-intensity exercise on most days of the week
- Avoid exercise involving the following conditions:
- Supine position after the first trimester
- Prolonged standing
- High risk of contact, falling, or abdominal trauma
- Altitudes greater than 5250 feet
- Scuba diving
- Stop exercise for any of the following signs or symptoms:
- Vaginal bleeding
- Calf pain or swelling
- Chest pain
- Risk of preterm labour
- Decreased foetal movement
- Leakage of amniotic fluid
- Dyspnoea prior to physical activity
By starting to incorporate physical activity into your daily life, you are also giving your little ones an amazing role model – teaching them that getting out and moving is great for the body and mind!