Weak Bowel Movements, Muscles – Causes and Symptoms

Bowel problems are common and typically presents with alteration of bowel habit like constipation and diarrhea. We all understand that bowel movements need to be frequent – for some people it is once or twice daily while for others it is several times in a week. The need to pass stool is signaled by contractions in the abdomen and an urge to defecate. When a bowel movement occurs there are typically strong contractions that push out stool easily. However, for some people the urge and control of bowel movements are weakened.

What is a weak bowel?

A weak bowel is a common term to describe a host of different bowel symptoms. Usually it is associated with constipation and is therefore described as weak bowel movements. Despite straining a person has great difficulty in passing stools. Weak bowel muscles may also be referred to as a weak bowel but this is a condition where there is fecal incontinence. In this condition the ability to hold back defecation is often due to weak pelvic floor muscles.

Constipation and bowel incontinence, are two different conditions. Therefore a weak bowel can be quite an inaccurate term to describe these conditions. However, the underlying meaning is largely the same – it indicates muscle weakness. With constipation this weakness may be with the muscles of the bowel wall whereas with fecal incontinence the weakness lies in the pelvic floor muscles.

Bowel Muscles and Movements

The vast majority of movement within the bowels is a result of muscles contracting and relaxing. Gravity plays a small role in facilitating movement but without muscle activity, movement in the bowels would not be possible. The contractions and relaxation of the muscles occur in a rhythmic fashion in sections of the gut. It is known as peristalsis and the primary purpose is to move food and fluids from the bowel until the remaining portions pass out of the rectum as stool.

However, the contraction and relaxation of muscles do not occur spontaneously. Instead it is under the control of nerves which are partially voluntary but largely involuntary. Weakness of the bowel muscles and bowel movements indicates a problem with the lower parts of the bowel, namely the colon, rectum and anus. It is also facilitated by muscles outside of the bowels, such as the pelvic floor muscles.

How does bowel movements occur?

Due to the process  of peristalsis, food is pushed through the upper gut where it is digested and then the nutrients are absorbed mainly in the middle and lower portions of the gut. Water is drawn out of the colon and solid stool is formed. It is stored in the lower part of the colon until defecation.  The stool is pushed into the rectum by strong contraction of the colon wall.

The filling of the rectum with stool stretches the rectal walls. This signals a person that there is a need to defecate soon. When appropriate a person strains by increasing pressure through the contraction of the abdominal and pelvic wall muscles. The anal sphincters which are muscles relax and the stool can be squeezed out of the rectum, through the anus and is then expelled into the environment.

About Weak Bowel Movements

Constipation is defined as passing stool less than three times in a week with difficulty in passing stool. Often the stool is hard and significant straining is required to defecate. Constipation is a common problem globally and is often not seen as a serious condition. However, it can be debilitating in many instances and lead to complications such as fecal impaction.


Constipation is a symptom. Apart from the infrequent bowel movements, straining to pass stool and hard stool there may also be other symptoms present. This includes a constant urge to defecate which does not subside after a bowel movement (typically described as an incomplete bowel movement). Abdominal pain and cramping may also be present and in rare cases there is also nausea and vomiting.


Many cases of constipation are due to unknown causes. It is believed that it is a result of slower than normal bowel motility and is referred to as functional constipation. Known causes of constipation include:

  • Inadequate fiber intake in the diet.
  • Insufficient water consumption.
  • Sedentary lifestyle.
  • Obstruction in the colon or rectum.
  • Nerve problems in the colon or rectum.
  • Muscle problems.
  • Hormonal abnormalities.

It is important to note that weakened pelvic muscles is one of the muscle problems that may lead to constipation. Chronic constipation can in turn lead to fecal incontinence. Therefore constipation and fecal incontinence are separate conditions that may be closely associated with each other.

About Weak Bowel Muscles

Bowel incontinence is a condition where the is difficulty in controlling bowel movements. As a result feces may be involuntarily passed out. The quanity of the stool expelled can vary from small amounts to a complete bowel movement. Fecal incontinence can be acute where it occurs once or twice typically when severe diarrhea arises, or it may be chronic where there is permanent damage to one or more structures that facilitate bowel control.


The main symptom of fecal incontinence is soiling of the undergarments as a person cann hold back the passage of stool. Diarrhea, constipation and excessive gas may also be present. Some patients report bloating as well. Fecal incontinence has a significant psychosocial impact on the person and can therefore contribute to psychological symptoms.


Fecal incontinence is more common in older women but depending on the underlying causes it can affect any gender of any age. Possible causes include:

  • Nerve damage
  • Muscle problems
  • Surgery (rectum or anus)
  • Rectal prolapse
  • ‘Stiffening’ of the rectal walls
  • Rectocele
  • Chronic constipation
  • Acute diarrhea

Dementia is a factor in fecal incontinence. Sometimes a person’s cognitive ability is impaired to a point that passing stool is done anywhere and at any time with no regard for hygiene or social norms. Similarly, people who are physically disabled may have difficulty in reaching a toilet in time when the urge to defecate arises. As a result they may soil themselves even though they have relatively normal bowel control.

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