Wed 21, Dec 2016

Patterns within the abdominal muscle wall in postnatal women

During pregnancy the abdominal wall is lengthened, to enable the uterus to expand as the baby or babies grow.

After the birth, the muscles of the lengthened abdominal muscle wall require retraining to assist them to return to their normal length and to function as an integral part of the core. This includes their coordinated action with the pelvic floor, the deep back muscles and the diaphragm, as they all work together normally to maintain continence, support the pelvic organs and provide spinal stability.

Correct abdominal muscle exercise techniques in the postnatal stage of a woman’s life are needed to also protect the recovering pelvic floor and to prevent it from further stretching.

Common abdominal muscle exercises such as sit ups and curl ups have been shown via real time ultrasound to cause excessive pelvic floor descent in some women. These exercises mainly work the upper abdominal muscles, and are not considered as ideal “early” postnatal abdominal exercises, as they do not specifically train the deeper and lower abdominal muscles.

Planks are also a common exercise choice, but for postnatal women they are a “strong” exercise that can engage the upper abdominal wall and external obliques while the deep abdominal muscles are not yet working well. Holding a plank creates pressure in the abdominal cylinder. If the lower abdominal muscle wall or the pelvic floor muscles are lengthened, this pressure will push down on these areas. Until core control is built up, including pelvic floor muscle control, these are not the best choice of exercise for recovery and safer choices need to be considered for postnatal women.

Interaction of the postnatal pelvic floor with the deep abdominal wall

3 graphs of pelvic floor muscle contractions

As the pelvic floor recovers from the effects of pregnancy and birth, it’s interaction with the deep abdominal muscles improves (with correct muscle training). Initially, as in graph 1, if the pelvic floor is weak and contraction strength and duration is reduced, it’s interaction with the deep abdominal muscles may not be felt. In the early weeks following the birth, some women will need to do both pelvic floor and deep abdominal (postnatal) bracing, each as separate exercises.

With correct pelvic floor and abdominal muscle training, as the pelvic floor improves from that shown in graph 2 to graph 3, the interaction between the pelvic floor and the deep abdominal muscle wall will return.

This means that ideally, when a woman draws in her pelvic floor, the lower abdominal muscle wall will also work. An initial screening baseline check in sitting position can give you some indication of where your client is positioned in their recovery stage. If you are unsure, encourage them to have a postnatal check with a women’s health physiotherapist first.

There are common patterns observed in working with clients when doing a baseline check of their early postnatal abdominal bracing pattern.

  1. The pelvic floor lifts but there is no connection yet with the lower abdominal muscle wall
  2. The pelvic floor lifts and there is a draw in of the lower half of the abdominal wall, below the belly button (correct action – PF Contraction A)
  3. The abdominal wall draws in but the pressure change created pushes down on the weakened pelvic floor, causing a bearing down action (Incorrect action – PF Contraction A)

Diagrams of correct and incorrect pelvic floor contraction

Excessive tension through the upper abdominals and breath holding are common faults and an indication that the client may be trying too hard. This has the potential to place downwards pressure on the pelvic floor muscles (incorrect action – PF Contraction A)

These patterns often occur in women who have done a lot of upper abdominal training before they were pregnant, as the upper abdominals are stronger in proportion to the lower and deeper abdominal muscle wall.

Retraining for these clients then requires “detraining” of the pattern, to release relative tightness in the upper abdomen and to enable the correct recruitment pattern in the lower abdominal wall and pelvic floor, with a normal breathing pattern.

One client who attended a regular postnatal program had a lot of difficulty learning the ideal pattern of recruitment, initially with consistent excessive upper abdominal muscle activity when she attempted to recruit her pelvic floor and lower abdominal muscle wall.  Later, after she had mastered the technique and rebuilt a moderate level of core control, she said she had competed in Karate at an international level when she was younger, and it had been a long-term pattern for her to “splint” her upper abdominal muscle wall.

She required a lot of detraining and then retraining to rebuild the deep abdominal wall activity in a coordinated way, with good pelvic floor action and no breath holding. As she built this, she was able to progress to leg loading and stronger training while maintaining correct action within her abdominal muscle wall.

Each postnatal client that you see is an individual and considering their past training history, together with their pregnancy and birth experience, is an integral part of planning a postnatal training program incorporating safe and progressive postnatal abdominal exercises. Go to Returning to sport or exercise after birth for more on safe return to exercise for postnatal women.

Written by Pelvic Floor First ambassador Dianne Edmonds

Dianne is a physiotherapist working at Peel Maternity and Family Practice with pregnant and postnatal clients in Mandurah WA. Dianne has written a series of pregnancy and postnatal core conditioning online courses for Australian Fitness Network, and is a fitnessU women’s (pre and postnatal) trainer and ambassador. She is also the founder and director of The Pregnancy Centre.

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