Let’s rewind the clock
Historically, pregnant women were treated as if they were ill – wrapped in cotton wool, told to relax, avoid strenuous exertion, and minimise stretching for fear of squashing the baby or knotting the umbilical cord. It was only in 1985(!) that the American College of Obstetrics and Gynaecology (ACOG) published its first guidelines for exercise during pregnancy.
These very first ACOG guidelines, albeit conservative and not entirely evidence based, were at least a starting point for women who wanted to be physically active during pregnancy, and they provided some guidance for the health care professionals who would advise them. The guidelines contained very specific exercise heart rate max and duration of 140 beats/minute and 15 minutes, respectively – which didn’t get you very much or very far with an exercise program.
We now know
that heart rate response is augmented by the additional blood volume and consequential increased cardiac output in pregnancy, and that a better indicator of exercise intensity is using the ‘talk test’ – an indicator of RPE (rate of perceived exertion) and level of breathlessness.
In the 1990s, pregnancy exercise researchers like James Clapp (considered one of the OGs of pregnancy exercise research) helped to expand on the understanding of the safety of exercise in pregnancy, clearing up the myths of miscarriage and placental growth. In fact, Clapp and his
researchers helped us better understand how the multiple physiological changes that occur in pregnancy on the cardiovascular and metabolic systems work to protect mother and developing placental unit from risk.
Comprehensive position statements from the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG), Canadian Society for Exercise Physiology (CSEP) and ACOG have supported how the multiple benefits of exercise in pregnancy far outweigh the risks – it is actually considered a ‘window of opportunity’ to begin exercising and it is actively encouraged for women to exercise at a moderate intensity throughout pregnancy.