The pregnancy workout picture Michelle Bridges deleted.

Here is my professional opinion (not judgement) based on 8 years clinical experience as a physiotherapist working in the area of women's health at a tertiary maternity hospital and in private practice. I feel sorry for Michelle for being in the spotlight here, because pregnancy is hard enough without having the scrutiny of a nation to deal with. Still, as she does try to be a role model for pregnant women, and even has an app in this industry, I think this information needs to be out there in the public domain for all to consider.

There are 3 reasons why lifting heavy weights in pregnancy can harm a woman.
2 of those 3 reasons cause 'silent strain'; harm that is not necessarily noticed by her or her personal trainer but predisposes her to undesirable complications. Those complications are incontinence, prolapse and rectus diastasis (6 pack separation).

1 --GENERAL JOINT STRAIN--

The first reason, that can cause noticeable harm, is joint strain or sprain. The interplay of several hormones in pregnancy causes laxity (stretch and looseness) of all ligaments in the body. Ligaments connect joints, so if they are sloppy they are less able to protect her joints under the load of the weight, predisposing her to strain in any joints that bear that extra load of the weight, including those in her back, shoulders, legs and pelvis. Good technique in lifting can mitigate this risk to some extent. This isn't silent harm. She'll notice it and she'll stop it if she cannot handle it.

2 -- ABDOMINAL STRAIN --

The second reason is the potential for 6 pack separation (known as rectus diastasis or diastasis rectii - a quick Google Image search will help you to understand this). As the foetus grows it passively stretches the abdominal muscles, connective tissue and skin. Muscle and skin tends to be able to slowly stretch and stretch and stretch without tearing (it loses its mechanical advantage but that isn't as relevant in this context), but connective tissue is not so fleshy and cannot stretch as well. There is a band of connective tissue spanning vertically along the midline of the abdomen, holding together two rows of rectus abdominis muscles. This connective tissue is called the linea alba. The linea alba has to passively stretch, or else it will tear. When it tears it is not felt, there is no pain because it is not innervated. A small tear in the linea alba is common, and it often just heals itself. The wider the separation, the more difficult it is for those two torn edges to find eachother again and heal. When they don't heal, it causes more abdominal instability, looks less aesthetically pleasing and can make a woman vulnerable to herniating part of the bowel through this space, although the latter is quite rare. People whose linea alba's tear earlier in their pregnancy have more time for it to divide further, particularly if they repeatedly contract a divided 6 pack. Those muscle bellies migrate further apart.

Here is where it gets tricky to understand by try to follow the logic.

We know with certainty that muscles which are contracted repeatedly (high reps) or very strongly (high load) have more tone and become tighter. We know that the 6 pack is recruited in most lifting activities, particularly in upright positions such as that depicted in Michelle's photo. We know that lifting weights under high load will strengthen and tighten the 6 pack.

A tight 6 pack is not desirable in pregnancy because it resists passive stretch of the linea alba, and that means the linea alba is more likely to just tear if it cannot stretch.

This concept is what we call 'clinical commonsense'. It is an extrapolation of evidence from the non-pregnant population to the pregnant population. There is a good reason for us to rely on clinical commonsense rather than seek to prove it.

Scientifically proving cause and effect in this context would require an experimental research design with three groups of women; one group who do no exercise, one group who we give 'clinically appropriate' core stability exercises to, and one group who we train with strong repeated heavy lifting. Then we'd measure their 6 pack separations throughout their pregnancy and postnatally and tell you with 100% certainty if heavy lifting causes an increased incidence of rectus diastasis.

(Connective tissue integrity tends to be an inherited trait, so it seems some people are blessed with better connective tissue than others. But we'd assume that randomly allocating groups would have roughly the same spread of tissue types across groups).

This clinical study has not happened and will not happen. No research ethics committee will approve scientific research on a pregnant women where the researchers know from the outset that they are likely to cause harm or adverse outcomes on one or more groups of women. This is why most medications are not approved for pregnancy - they simply haven't been approved for clinical trials.

I can tell you that women's health physiotherapists around the world pretty much unanimously agree with this concept: encourage exercises that recruit the transverse abdominis in pregnancy without adding load to the rectus abdominis. This includes discouraging lifting heavy weights, including toddlers, so far as possible.

3. -- PELVIC FLOOR STRAIN --

Here is a harder biomechanical concept to explain. The pelvic floor is mixed muscle and connective tissue at the base of the pelvis. Think of it as the bottom of the abdominal canister, and this abdominal canister has sides and a roof (diaphragm) that can move and vary in their tension. Any one of those sides can tension and vary the pressure in the canister. An example is when the cough at the diaphragm causes increased pressure in the abdominal canister - and this causes the (pelvic) floor of the abdominal canister to bulge downwards, which strains the pelvic floor and can make it let got of it's hold on the urethra, making you leak a bit of urine.

If the 6 pack is contracting tightly it increases the pressure in the abdominal canister. It increases even more (much much more) if the diaphragm is pressed down too, like when you hold your breath when straining to lift a heavy weight. This extra pressure bears down on the pelvic floor, causing it to bulge. Some women's pelvic floors are stronger than others, have better endurance than others, and better quality connective tissue than others. This explains why some women pee when they lift heavy weights and some don't. But do not think that peeing yourself is some sort of safety threshold; it is a continuum of strain. At a certain point that causes you to pee and that 'silent harm' is no longer silent. That point is well beyond the point of what is good for your pelvic floor.

Whether Michelle notices it or not, lifting heavy weights does bulge down on her pelvic floor, putting it under more load and putting it into a lowered and lengthened position. She can contract the muscles, but her contractions are not likely to be strong enough to protect them from the strain bearing down on them.

Regardless of how much she has trained in the past with weight lifting, she has not trained with the additional weight of the foetus on her pelvic floor. The weight of the foetus has been silently straining her pelvic floor day in and day out for several months and thus her pelvic floor endurance is already challenged. Lifting a heavy weight will increase the intra-abdominal pressure on it, and challenge it further.

This can lead to incontinence and prolapse.

Incontinence and prolapse are actually MORE COMMON in athletes. True story.

Prolapse affects at least 1 in 3 women in their lifetime. I see it a lot post menopause but also antenatally and postnatally. It is not often talked about and it is so poorly understood, particularly by personal trainers.

I know it is a lot to take in. Here is a resource I developed with links for further learning if you are ready to confront this reality.

http://www.nextstepphysio.c...

FYI Mamamia, Bridges appears to be front squatting, or a clean, not deadlifting. Guidolin is deadlifting in her pic.