Guidelines for Exercise during Pregnancy

The focus of this article is to briefly overview the North American medical community’s existing prenatal fitness guidelines, and explore how they can help shape your beginner or advanced athletic workout.

Not all women are athletes, but pregnancy will make an athlete out of you. Train accordingly.

I tell this to my pregnant clients, friends and family all the time: there is no other time in your life that you'll gain 25 to 40 lbs. in nine months, experience full-body joint aches and pains, and, in the end, endure a workout lasting an average of 12 hours -- AKA "giving birth". Indeed, not all women are athletes, but pregnancy will make an athlete out of you. Train accordingly.

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My obstetrician (OB) agrees. When we first met, I asked him for his opinion on exercising while pregnant. His reply stuck with me: "Would you run a marathon without training for it?" I guess not. It seems crazy now, but only a generation or two ago, women were warned by members of the medical community to be cautious during pregnancy -- it was a seemingly delicate condition -- sometimes to the point of bed rest. But fast forward to today: expectant moms are encouraged to stay active through regular, gentle exercise. And the anxiety about a pregnant woman's fragility has begun to dissipate.
 

WHERE TO START

With 13% of Canadian women of childbearing age being overweight, exercise during pregnancy is more important than ever before. But it doesn't have to be daunting. It starts with talking to the healthcare provider who is monitoring your pregnancy: whether you are new to exercise or a seasoned athlete, it is always best to be cleared for physical activity by your OB or midwife, who will be able to identify factors that may increase the risk of fetal or maternal injury. I often recommend that my clients start informing themselves by reading the PARmed-X for Pregnancy (Physical Activity Readiness Medical Examination) and formulating useful questions to ask their healthcare provider. This document is a health assessment to clear you for safe exercise, and is also an excellent resource providing general guidelines to an exercise program for pregnancy.

Once you have your OB/midwife's green light, you can consult a prenatal fitness professional.

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EXERCISE PROGRAMMING CONSIDERATIONS

When working with pregnant women, I offer three solid rules of thumb to follow during aerobic activity and weight training:

1. FITT Principle:
FITT stands for Frequency, Intensity, Time and Type -- the four variables in a workout that can increase or decrease the challenge. Recommendations for a woman's workout are suggested depending on her athletic experience.

Frequency (i.e. # of exercise sessions per week):
- Beginner athlete: 3x/week
- Seasoned athlete: as per pre-pregnancy levels ("as previous"), up to 6x/week

Intensity (i.e. level of challenge, which can be measured many ways, including):

  • Talk Test: see below
     
  • Rate of Perceived Exertion: see below
    - Beginner athlete: 12-14 (somewhat hard)
    - Seasoned athlete: as previous
     
  • Heart Rate:
    - Beginner athlete: 100-144 bpm, depending on age
    - Seasoned athlete: 130-156 bpm, depending on age

Time (i.e. duration of workout):
- Beginner athlete: 15 min
- Seasoned athlete: as previous

Type: see below

2. Talk Test:
The Talk Test is used to subjectively grade the intensity of your workout. The aim is to exercise such that you're just too out of breath to carry a conversation comfortably. In other words, if you cannot carry a conversation, you need to slow down; if you can chat with ease, it's time to turn up. If you are new to exercise, the talk test will tell you when you're working into a caution zone -- usually around 70% of your maximum heart rate.

3. Rate of Perceived Exertion (RPE):
This is a subjective score on a scale from 6 to 20; 6 is considered to be "very very light" and 20 is considered "very very hard". The PARmed-X recommends a range of about 12 to 14 ("somewhat hard") as appropriate for most pregnant women. Seasoned athletes are usually able to push themselves much further -- and a good prenatal fitness expert will be able to help you determine how hard to push.
 

TYPES OF EXERCISE

Whether a beginner or an experienced athlete, there are four types of exercise that I recommend to pregnant moms:

1. Aerobic activity is defined as what gets the heart pumping -- cardio, as we sometimes call it. By the end of your pregnancy, you will have approximately 50% more blood volume circulating in your body, in order to circulate oxygen and waste to/from your baby (source: "Pregnancy Day by Day", Herer and Blott). This means your heart works harder, even at rest. If your heart isn't trained to handle this additional stress, you might wind up feeling lethargic and struggling with everyday activities (e.g. climbing stairs). Thus, doing aerobic exercise strengthens the heart, allowing it to more readily meet the evolving demands of pregnancy. The Canadian Society for Exercise Physiology (CSEP) recommends 3-4 sessions per week, each session lasting 15-30 minutes long.

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2. Strength Training -- squat, squat, squat. And when you're done? Squat some more! Virtually all pregnancies will result in some degree of a hyperlordosis (an extra arched lower back), but back pain is greatly decreased with strong glute, back and core muscles. Furthermore, 100% of pregnancies will result in diastasis rectus abdominus, requiring you to strengthen your rectus abdominus and transverse abdominus with proper modifications. As such, squats and core exercises are critical before, during and after pregnancy, modifying at each stage of the journey; make sure you have a prenatal fitness professional to help guide this evolution.

3. Sports and Instructional Classes: the body was designed to move. And while pregnancy might not be the easiest time to start a new sport, an expecting beginner can safely participate in athletic activities (like prenatal yoga and pilates) if gently and properly introduced. Similarly, an athlete who has played a sport prior to pregnancy may be able to safely continue participating -- possibly for a part of the pregnancy or throughout the entire pregnancy -- given the proper instruction and tools.

Most of my pregnant runners stop running if they begin to experience too much pressure in their pelvic area, which occurs at a different time for each woman. However, some women feel well enough to run through their entire pregnancies. And while most women will cease high risk activities (e.g. contact sports, or those with a high risk of falling), others may be approved by healthcare professionals to continue. For example, I recently worked with a client who is an equestrian, and her OB cleared her to continue riding horses well into her third trimester, along with a list of "red flags" to look out for. As it turned out, the OB was also a seasoned horse rider, who was able to understand her athletic needs and provide guidance accordingly.

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4. Stretching. During pregnancy, you will feel tightness in your body's muscles, and due to hormonal changes your joints will increase in laxity as you grow. If not modified for your specific stage of pregnancy, traditional static stretches may cause a problem. A safer way to stretch is by focusing on dynamic stretching or to use equipment like foam rollers or The Stick to lengthen the muscle tissue, or a lacrosse ball to address knots in your muscles ("trigger points").


OTHER TIPS FOR EXERCISING WHILE PREGNANT

  • Minimize your risk of falling. The risk of falling isn't so much for the mother's safety as it is for the baby's. A sudden fall can cause injury to the placenta, which is your baby's lifeline, providing all the blood and oxygen necessary for survival. With this in mind, you might want to reconsider participating in high-risk sports (i.e. full contact sports such as rugby and soccer). However, other sports might become less of a risk if just slightly modified, such as running on a treadmill indoors instead of running outdoors during the winter.
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  • Stay hydrated! Your body requires much more water just by being pregnant. For example, I mentioned earlier that by the end of 40 weeks, your body will carry up to 50% more blood volume -- this blood includes water, of course. You will also sweat more while pregnant. Now, add exercise and an increasing body weight into the mix: you will sweat a lot. Be mindful about drinking water, and check in with yourself throughout the day; if you feel thirsty, you're already dehydrated. One way to measure if you're well hydrated is by examining your urine colour: it should be a very light yellow colour. The darker your pee, the more dehydrated you are.
     
  • Wear appropriate clothing. Your pre-pregnancy workout gear may at some point become too restrictive to allow for comfortable movement. The band in your pants/shorts might start to feel tight at approximately 20 weeks (or earlier if it's not your first pregnancy). Similarly, bras will start to feel tight around the ribs as the rib cage expands (about 1-2 inches in diameter), and may cause heartburn or difficulty breathing. Select a bra that properly supports your growing breasts -- this allows for comfort during high impact activity. The bonus is that you will likely use this bra again after giving birth, if you exercise while nursing!
     

KNOWING WHEN TO STOP

An absolute contraindication is a "situation which makes a particular treatment absolutely inadvisable," whereas a relative contraindication is a situation that requires caution. Your health practitioner will be able to tell you if you have any contraindications, including common absolute contraindications such as an intrauterine growth restriction (IUGR), placenta previa, or an incompetent cervix. In each of these three situations, exercise of any kind is generally not advised until after the situation has passed or is under control.

And sometimes, even with a healthy pregnancy, some situations may arise while exercising where you should stop immediately and tell your healthcare provider ASAP. Examples include, but are not limited to:

  • vaginal bleeding
  • abdominal pain
  • unexplained faintness, dizziness, fatigue
  • sudden swelling of ankles, hands or face
  • deep ache in leg(s)
     

EXERCISE ALONE IS NOT ENOUGH

A final thought: much like physical activity while not pregnant, prenatal exercise is but one of three equally important factors to achieving good health. The other two are proper nutrition and rest/recovery, and they are extremely important in ensuring that you can maximize the effects of your workouts. Do not forget about these!

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Additional sources:

  1. PARmed-X for Pregnancy (Canadian Society for Exercise Physiology (CSEP))
  2. "Active living during pregnancy: physical activity guidelines for mother and baby" (endorsed by CSEP)
  3. Health Canada Prenatal Nutrition
  4. Exercise and Pregnancy (Society of Obstetricians and Gynaecologists of Canada)
  5. American Congress of Obstetricians and Gynecologists