How to exercise safely during pregnancy


Barsky says that the most common myths about exercising in pregnancy include:

  • Pregnant woman should  take it easy during pregnancy
  • You can exercise gently by going for walks
  • You cannot raise your heart rate above 140 beats per minute
  • You cannot use weights
  • You can’t do abdominal exercises if you are pregnant.

“If you have never exercised before, the main thing is to find a trainer who has experience training pregnant women and appreciates the body changes. You would want to start off training initially twice a week at a moderate intensity for 30 minutes to an hour. As you get fitter, you will be able to increase the frequency and intensity of your training,” she explains.

In terms of types of exercises, most forms of recreational exercise are fine but make sure that your programme includes cardiovascular and strength training, as well as flexibility and balance.

However, if you have been exercising regularly prior to falling pregnant, Barsky says there are two core things which would need to be modified if you are training on your own: your intensity and position.

“You will naturally feel yourself slowing down, which can be quite frustrating and also tempting to push extra hard. Your intensity needs to be such that you break a sweat but are still able to hold a conversation. Position-wise, you would want to avoid lying flat on your back and avoid periods of motionless standing,” she says.

Why pregnant women need to exercise

There are many reasons why it is important to exercise when you are pregnant, says Barsky:

  • Exercising in pregnancy helps improve your fitness and endurance for labour.
  • Placentas of exercising women have been found to be of better quality than their non-exercising counterparts. This shows an improved delivery of nutrients to the growing foetus. (Clapp and Rizk 1992 American Journal of Obstetrics and Gynecology ; Jackson et al 1995 Placenta)
  • Women who exercise during their pregnancies heal faster after delivery regardless of their mode of delivery.
  • Exercising in pregnancy helps control the amount of weight gained during the pregnancy.
  • By exercising in your pregnancy, you return to your pre-pregnant shape faster.

The heart rate confusion

One of the first things pregnant women who begin exercise hear is that they shouldn’t get their heart rate too “high”. However, as pregnancy affects your resting heart rate and thus your heart rate during exercise, it’s not always the best indicator or effort. It is also why the rather old fashioned method of keeping your heart rate below 140 beats a minute during exercise has been shown to be ineffective.

She explains that heart rate refers to the amount of times your heart beats in a minute. Traditionally, this is an easy way for someone to measure the intensity of their training. The harder you train, the faster your heart beats. Everyone has a maximum of how high they can push their heart rate based on their age. There are a few formulas you would then use to determine your heart rate range – this would be your target heart rate during your training session.

“But in pregnancy, heart rate is no longer an accurate indicator of exercise intensity. This is mainly due to the physiological adaptations that happen in your body during this time. During pregnancy your resting heart rate goes up, there is only so much reserve left for your heart to pump faster and your heart’s maximal rate gets ‘reset’ to a lower rate. 

“Also, many other factors affect your heart rate too – such as your age, level of fitness and how well hydrated you are at the particular time that you choose to exercise.”

According to Barksy, she prefers to use the method of 'RPE – Rate of Perceived Exertion’. 

“The RPE uses a scale (most commonly Borg’s) where you would score yourself out of 20, where 20 is the hardest you could possibly train. In pregnancy you would want to score yourself between 12 and 14. Research has correlated this to a moderate intensity of training.

“This is the reason why the heart rate limitation of 140bpm was removed from international Obstetric and Gyneacological guidelines for exercising in pregnancy,” she adds.

Exercise in the first trimester

Interestingly, there are no official guidelines per trimester, rather the guidelines for exercise during pregnancy apply over the whole period.

However, as Barsky points out, the main concern during the first trimester is that of over-heating. In order to avoid this you would need to do the following:

  • Drink cool water during your training session
  • Wear cool comfortable clothing
  • Exercise in a well ventilated environment
  • Don’t exercise in extreme heat
  • Don’t exercise if you are running a temperature.

Exercise in the second and third trimester

By the time you reach your second trimester you should be over any of the common gripes of the first 12 weeks such as morning sickness and you will be feeling great. This is often referred to as the ‘honeymoon trimester’ and exercise for the next few weeks will be a pleasure as you will have lots of energy.

By the third trimester, if you have been exercising regularly, you should still be able to continue, although Barsky says here your primary concern will be to avoid going into premature labour.

“This is why at Preggi Bellies we do not start new clients if they are more than 30 weeks pregnant. Similarly, if you have not trained regularly up to this point, the third trimester is not the time to start.

“The reason for this, is that it is in this stage of pregnancy the uterine muscles start figuring out how to work together - otherwise known as Braxton-Hicks contractions. The uterus becomes sensitive to stimulation and will contract as a result.

“If you experience contractions during an exercise session that do not subside with decreasing intensity – this is your warning sign to stop. If the contractions still don’t subside or become more intense and frequent you will need to see your gynaecologist or midwife as a matter of urgency as you could be in labour,” she says.

When not to train

Since you will be exercising for two, you need to pay extra attention to any signals your body may send you during exercise that you might be over-doing it. Barsky says that there are a number of medical and obstetrical contra-indications as to when you should not train, so check with your gynae that it is safe to train before you start a programme.

However, if you experience any of the following you need to stop exercising immediately:

  • Excessive shortness of breath
  • Chest pain or palpitations
  • Severe dizziness
  • Painful uterine contractions or preterm labour
  • Leakage of amniotic fluid
  • Vaginal bleeding
  • Excessive fatigue
  • Abdominal pain, particularly in back or pubic area
  • Severe pelvic girdle pain
  • Reduced fetal movement
  • Headache
  • Muscle weakness
  • Calf pain or swelling.

 Source:  Dr Etti Barsky (MBBCh, MSC Sports Science), training director of Preggi Bellies South Africa.


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