As a baby grows, a woman’s core musculature stretches to accommodate the growing fetus. This means forward stretching that also pulls forward on the spine causing increased lower back arch or hyperlordosis. Increasing weight of the fetus in addition to core muscles under tension means a change in the center of gravity so the entire body is adjusting.
It’s important when initiating a movement to first tuck tailbone by contracting obliques (posterior tilt of the pelvis) to engage transverse. Doing this will brace your core creating a secure canister to safely perform the movement. Bracing is important during pregnancy because it engages the core properly to build mind/body connection so the muscles can work safely against gravity as the fetus grows. It’s also great practice for postpartum when healing through bracing must occur first.
Substitute flexion exercises sit-ups, knees/toes to chest/bar, GHD sit-ups with:
Knees to chest or straight leg raises either hanging from bar (which can get uncomfortable in later weeks) or between two boxes can be performed if client is FIRST engaging obliques to posteriorly tilt pelvis THEN performing movement.
I’m not saying any these movements are ‘bad’ during pregnancy. We don’t know the outcome of a woman’s abdominals postpartum after repeated, uncontrolled, repetitions during pregnancy. We can expertly guess it’s not beneficial, so there’s a point where we stop potentially damaging movements in favor of more appropriate ones to reduce risk of long term injury.
And we aren’t far off. There are many, many cases of women who continued high-intensity exercise through pregnancy without any modifications and ended up with severe diastasis recti and/or pelvic floor issues. These two extremely common issues take months if not years to heal, even when appropriately addressed by a women’s health physical therapist. It’s our jobs as coaches to do no harm and I don’t think you want to cause injury to your clients. Take modifying/substituting for a woman’s body seriously.
Consult a physician before performing this or any exercise program. You as the user are responsible independently for use of any fitness programs or equipment and assume the risks of any resulting injury.