Strength training makes up a lot of what we do in CrossFit programming. We're familiar with sets and rep schemes, strength programs, progressive loading, deloading, etc etc... but what, then, are the latest guidelines for strength training when you're pregnant?
The IOC (international Olympic Committee) has released guidelines specifically aimed at the elite athletic population (Bo, 2018), and the good news is that unless you have a high risk pregnancy there has been no evidence to show that continuing to train throughout pregnancy has a negative effect on the mother and foetus.
But with regards to strength training itself. Honestly? If you're searching for clinical research you're not going to find much. In fact the heaviest load used in pregnancy clinical research stretches to 20kg... and that's where the guidelines end. This means that a lot of pregnant lifters are currently under-informed: after all - 20kg is usually close to a warm-up weight in CrossFit.
This article, written in partnership with Nicola Rutty, sports and musculoskeletal specialist physiotherapist who works specifically with CrossFit athletes.
Please note: this is generalised guidelines on strength training in pregnancy in general. Each pregnancy is different, and every woman's baseline fitness and strength will be different. Unfortunately there is no "gold standard" but we have taken what we know to be the most current information we have from Australia, the UK, Canada and Norway and from the very best evidence that we do have available. Women who are competing or training greater than the recommended guidelines should seek supervision from their obstetric care provider.
1. You can continue to lift during pregnancy
First things first, don't stop strength training! Keep going. In fact strength training is probably the most important element to keep in your pregnancy programming. Now we're not talking 1 rep maxes here, but from a physical standpoint, maintaining a level of compound strength can help with managing the increased demands on your skeletal system as you progress through pregnancy. Being fit and strong as you head towards giving birth will undoubtedly stand you in excellent stead for managing your delivery and recovery too.
From a practical sense, strength training is a great choice as it can be modified easily (way easier than modifying cardio pieces) to make adjustments the physiological changes you'll experience throughout the different trimesters, and also a growing belly. We can modify weight, repetitions, range of movement and intensity.
Squatting in particular has been shown to help with strengthening and conditioning the pelvic floor and reducing symptoms of back pain in pregnancy. Although as you go through pregnancy you might find you need to alter the lift: back squat can shift to front squat as your belly grows to reduce the strain on your spine, and the depth can reduce to a box squat. Learning how to breathe in your lifts is also pretty vital.
You can learn this technique here: in our free video The Pelvic Floor, The Core & The Breath
2. Caution any lifting movement that includes physical contact to your belly
We need to consider the benefits vs risk of performing movements/exercises that could cause physical contact on the foetus, like power or Olympic lifting and gymnastics (yes, gymnastics is still strength training). It is true that the amniotic sac is incredibly durable but it's not wise to test the theory.
- Consider modifying power and Olympic lifts as your belly grows
Snatches and cleans involve a bar path which is very close to your body. As your belly grows you have one of two choices, to keep the bar close and risk a 'bump' OR to change the bar path. The former doesn't need further elaboration, but regarding the latter: if you continue to change your bar path through pregnancy, your neural system will remember this post-pregnancy, making your lifts more difficult to re-program postpartum. Remember how long it takes to pattern a snatch? Is it worth snatching 'til your waters break and then having to relearn how to snatch all over again postpartum? Something to think about.
When you feel you need to change the bar path, start using dumbbells instead of barbells to avoid risk of belly contact is a great option especially in later stages of pregnancy. For deadlifts, as your bump grows you might find a wider sumo stance is more comfortable/achievable.
- Swap out bar or ring muscle ups from early on
It's just not worth the risk of a bump or a fall from height. Try modifying first to pull ups and dips, and later on to ring rows.
3. Modify lifting or strength building movements that cause coning or doming
- Caution with pulling movements
You also want to be mindful of coning or doming on pulling movements in general - please see our 8 Exercises to Avoid as a Pregnant Athlete article for more info on this.
- Caution core-specific exercises
A lot of abdominal strength training can make a diastasis recti (the separation of abdominal muscles) worse.
For more information on DRA, or diastasis recti abdominis, please head to our resources page and download our free Diastasis ebook
From your second trimester GHDs, sit ups and toes-to-bar will now need modifying. Instead (however 'boring' they might seem) lower impact 'Pilates'-based core exercises are right up there with recommendations. See toes-to-bar in a workout? Choose Dead-Bug instead. See sit-ups in a workout? Choose Bridging. Plank? Choose Side-Plank to stop the load going through your abdomen.
- Learn how to coordinate a decent pelvic floor squeeze with your whole core system and the breath.
This technique helps you to strengthen your pelvic floor to manage the increased demand on it from 1) your growing baby and 2) continuing to exercise during pregnancy.
You can learn this technique here: in our free video The Pelvic Floor, The Core & The Breath
4. Consider Reducing Load
We love lifting heavy weights! A recent poll on Hatch Athletic showed that 87% of our pregnant and postpartum mamas would choose lifting heavy over all other exercise modalities.
I'm afraid to say that pregnancy is not the time to be trying for a 1RM, or even a 2RM for that matter. Avoid lifting heavy, heavy things. Keep things in a lighter zone were you don’t have to heavily breath hold or brace, which increases intra-abdominal pressure. You should also be aware of the affect of the "valsalva manoeuvre" or what we also call breath holding ‘pre-lift’, which can cause a rapid increase in blood pressure and decrease blood flow to the foetus. Although unfortunately the repercussion here on the foetus remains unknown (give us more studies please!) but as a result it's better to avoid it excessively.
Here's Nicola's suggestion on pregnancy lifting guidelines based on your normal percentages:
As well as reducing the weight you can consider modifying the lift. Begin by reducing the movement distance, therefore the velocity and thrust needed to shift the weight (i.e go from a hang and consider catching a lift in a power position) and as you progress through pregnancy, consider swapping out the barbell or dumbbells or kettlebells instead.
5. Exercises on your back
Nervous with a bench-press? In the past, women were warned off doing any exercises on their back but it's not considered so black and white anymore. These guidelines were for sustained periods on your back in the later weeks and months of pregnancy, i.e. sleeping or lying for hours at a time. This is due to reducing the blood flow to both you and your baby due to compromising the blood flow in vital blood vessels.
The general consensus these days is after 28 weeks pregnant you may lie on your back for short periods of time (2-3 minutes), for instance Bridging or Bird-Dog, and the benefits of these exercises outweigh the risks. However, change up any lifting on your back, i.e. chest press, to a 45 degree set-up as this can increase intra-abdominal pressure.
If you feel unwell or light-headed whilst lying on your back in any exercise modify the position to an incline set-up.
6. Avoid Weight or Barbell Cycling that takes you >90% HRM
Very high intensity exercise will peak your heart rate quicker in pregnancy so look out for long metcons, exercises racing 'for time' and barbell cycling pieces. An RPE (rate of perceived exertion score) scale doesn’t always have a direct correlation to heart rate, so we recommend using a heart rate monitor to keep an eye on things. The 140bpm guidelines are very outdated now. The most up to date recommendation for athletes is to stay below 90% of your heart rate max (HRM), which will happen quicker than you think, especially if you're in the later stages of pregnancy!
Most women during pregnancy will know where their heart rate limit is before they start experiencing any symptoms and will monitor this during a session and keep well below. More rest is always suggested during pregnancy and keep the intensity to a point of being able to keep a very puffy conversation.
Some other things worth mentioning...
- Avoid excessive heat, so hot summer days in a box without air con should be avoided or training in a high altitude environment. (Not that we can travel due to COVID anyway!!) Drink PLENTY of water to maintain hydrated.
-Trust yourself and what your body is telling you when training. While engaging in exercise during pregnancy, the following may serve as warning signs to stop exercising: vaginal bleeding, regular painful contractions, amniotic fluid leakage, prolonged shortness of breath, dizziness, headache, chest pain, muscle weakness, calf pain or swelling. You're sensible women, don't take any unnecessary risks ladies, it's just not worth it.
- Due to the lack of scientific research the suggestions in this article can be used to guide someone in their decision-making in a CrossFit and/or strength training environment during pregnancy. This should not be substituted for your healthcare professional (doctor, physiotherapist or midwife) who knows your pregnancy and can better understand and guide you through your pregnancy
- Don’t compare yourself to others: pregnant friends or athletes on social media. They may have been able to do things that you cannot and vice versa.
The good news is that the body is an amazing adaption machine, if there is a small period of your life were you cannot go as heavy as you would like or as hard as you normally would, that’s okay. You WILL get back to that stage again, trust me! Be kind to yourself in this relatively short phase of your training.
Nicola has worked as a private practice musculoskeletal physiotherapist for the past 5 years. She is also a keen CrossFit competitor over in the WA coast with an interest in treating and guiding females seeking to be active and exercise.
Many thanks to Luana Joplin @joplinlu, Brooke Shannan @brookeshannan and Grace Hall @grace_pt_thestrongtribe for their wonderful pregnancy lifting photos .