Many expectant mothers are confused about the what, where and how of exercise during pregnancy. It is important to remember that pregnancy is a normal condition and not an illness. Thus for most women it is possible to stay active and continue their sport or activity through the majority of their pregnancy. There are many benefits to exercising during pregnancy, and in fact, the current Australian current guidelines recommend it!
A woman’s body is undergoing constant mechanical, physiological and emotional changes throughout her pregnancy. The most obvious change is weight gain (average 10-15kg), which leads the centre of gravity to be shifted forward. This can affect balance and put strain on the back and pelvis. It is for this reason that care should be taken with any challenging balance or agility type exercise during pregnancy.
A pregnant woman will experience an increase in resting heart rate (HR), and also a decrease in maximal heart rate. It is important to not use your previous maximal HR as a guide for exertion. Intensity of exercise can be monitored by the mother’s rating of perceived exertion eg You know you’re at a good exercise intensity when you can talk normally (but cannot sing) and do not become exhausted too quickly.
A hormone called relaxin is released during pregnancy, which causes increased laxity of ligaments, especially around the pelvis. As one can imagine, this is very important in preparing for childbirth
When it comes to exercise care should be taken with change in direction (agility exercise) and excessive stretching during activity. Strengthening exercises (particularly core strength exercises) may also decrease the potential of injury to these joints.
During the second trimester of pregnancy, the development of blood vessels to supply the growing placenta will cause blood pressure to fall. From approximately the fourth month, pregnant women should avoid rapid changes of position, both from lying to standing and vice-versa, so as not to experience dizzy spells. Leg exercises done whilst lying on the back should be avoided after the fourth month as the weight of the foetus can slow down the return of blood to the heart. Try to modify these exercises as most can be done lying on the side. Prolonged periods of motionless standing should also be avoided.
As pregnancy progresses, the body’s ability to transport oxygen improves. This is known as our V02 Max. This adaptation is designed to meet the needs of the growing foetus. This means that oxygen supply to other parts of the body, including working muscles, also improves. These cardiorespiratory adaptations are potentially advantageous for performance after the baby is born. During pregnancy the advantages are offset by changes in weight, blood pressure and ligaments, and by the need to ensure oxygen supply to the foetus. Post Birth this window for improved performance generally goes unnoticed due to changes in sleep habits, breast feeding and stress of managing a new born.
There are no studies to date that show an association between exercise and adverse outcomes for the foetus. There are however some areas where concerns have been raised
It is therefore recommended that exercise in the third trimester be limited to three sessions or less and not be as intense as earlier in the pregnancy
The current advice is that each woman should discuss her wishes with her doctor and take into consideration the type of sport, pregnancy status and her history of participation in that sport
In general, healthy women who have uncomplicated pregnancies can continue their previous exercise program after consultation with their doctor. It is also now considered safe to START an exercise program. No studies have determined a safe ‘upper’ limit of exercise but as pregnancy continues, increased size and fatigue generally cause most women to lessen their participation.
The current guidelines recommend approximately 30 minutes of moderate intensity exercise on most days of the week. By the third trimester no more than three sessions per week of vigorous exercise are advised.
Extreme high temperatures, for example bikram yoga
jogging or running – if this was already an activity prior to pregnancy and should be discontinued during the 2nd and 3rd trimester due to the impact on pelvic floor and the pelvis.
When it comes to exercising throughout your pregnancy, listen to your body -If something doesn’t feel right, stop and seek advice. Remember to stay hydrated and keep calorie intake up especially if exercising over prolonged period of time. Always ensure adequate sleep and rest and avoid exercising in high heat and humidity. If doing a class, always alert the instructor to the fact you are pregnant. And, most importantly, be flexible and adaptable to change in training programs and expectations – we want you to stay active throughout your pregnancy so don’t feel disheartened if your plans change.
Catherine is a keen runner and Osteopath in Ocean Grove / Barwon Heads - If you have any questions please reach out as she is here to help
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