Planks are a popular core exercise used to build strength in the abdominal muscles, shoulders, and back. During pregnancy, the safety of this exercise changes dramatically as the body adapts to a growing fetus. Standard planks are generally safe throughout the first trimester if performed with good technique and without discomfort. However, the risk increases substantially after this early stage, requiring modification or substitution. Any exercise routine during pregnancy, including the decision to modify planks, should always be cleared by a healthcare provider.
The Safety Timeline: When to Stop Standard Planks
Standard planks become increasingly risky and should be regressed around the transition from the first to the second trimester (typically 12 to 16 weeks). This shift is due to physiological changes that increase intra-abdominal pressure (IAP), which is the pressure within the abdominal cavity. As the uterus grows, this pressure naturally elevates.
Performing a standard plank forces this heightened pressure directly against the abdominal wall, straining the linea alba. The linea alba is the connective tissue running down the center of the abdomen, joining the rectus abdominis muscles. The downward force from the plank can overstretch this tissue, which is already softening due to pregnancy hormones.
A visible sign of excessive pressure is “coning” or “doming,” appearing as a ridge or bulge down the center of the abdomen. If bulging is observed at any point, the movement must be immediately modified. While the plank position does not carry the risk of Vena Cava Compression like lying flat on the back, the risk of abdominal wall damage from IAP is paramount.
Understanding and Checking for Diastasis Recti
Diastasis Recti (DR) involves the separation of the rectus abdominis muscles. This separation occurs because the linea alba stretches to accommodate the growing baby, a process common in pregnancy. Core exercises like standard planks, which demand significant force, can exacerbate this separation by pushing against the weakened midline.
Checking for Diastasis Recti
A self-check can help determine the width of the separation, though a professional assessment is more accurate.
To check for DR:
- Lie on your back with knees bent and feet flat on the floor.
- Place two fingers horizontally on the midline of the abdomen, near the belly button.
- Gently lift the head and shoulders about an inch off the ground, engaging the abdominal muscles.
- If a gap is felt between the muscle ridges, measure its width in finger-widths.
A separation wider than two fingers is typically considered DR. If a gap is detected, all high-pressure core work, including standard planks, should be immediately stopped or modified.
Safe Plank Modifications and Form Adjustments
To maintain core strength without risking abdominal separation, the standard plank must be modified to reduce the gravitational load on the linea alba. The Incline Plank is an effective modification where the hands are elevated on a stable surface, such as a sturdy bench, chair, or wall. Elevating the upper body decreases the angle of the body relative to the floor, which significantly reduces the pressure placed on the anterior abdominal wall.
Another safe adjustment is the Kneeling Plank, performed from the knees rather than the toes, keeping the hips aligned with the shoulders and knees. Both modifications require maintaining a neutral spine, avoiding any arching in the lower back or sagging of the hips. The most important form check is ensuring there is no visible coning or doming during the hold.
Proper breathing mechanics are also fundamental. Instead of holding the breath, which spikes intra-abdominal pressure, exhale while engaging the core muscles. This controlled breathing helps recruit deep abdominal muscles and manages pressure effectively.
Core Strengthening Alternatives During Pregnancy
For those needing to move away from planks entirely, several exercises safely and effectively focus on the deep core stabilizers. The primary goal is to engage the transverse abdominis (TA), the deepest abdominal muscle layer that acts like a natural corset to support the spine and pelvis. Strengthening the TA is a more productive focus than working the superficial rectus abdominis during pregnancy.
The Bird-Dog exercise is performed on all fours, extending one arm forward and the opposite leg back, which requires the TA to stabilize the torso against the movement. Standing core work, such as a modified Pallof Press, uses resistance to train the core to resist rotation, engaging deep side abdominal muscles without placing downward pressure on the linea alba.
Pelvic Floor exercises, commonly known as Kegels, are also a direct way to strengthen the deep core system. These involve contracting the muscles used to stop the flow of urine, which works in coordination with the TA. These alternatives build foundational core stability without the high-pressure risks associated with traditional planks.