4 or less bowel motions per week

Research shows that the most common intestinal transit pattern in healthy adults is a 24-hour cycle, meaning one bowel movement roughly every day. In the largest prospective population study available, this 24-hour rhythm was observed in about 40% of men and 33% of women, making it the single most common transit pattern and physiologically “normal,” even though it is not experienced by the majority of the population, it is widely regarded as a sign of optimal colonic function.

Clinically, however, 4 bowel motions per week also falls within the experience of the vast population and can also be considered normal, providing the stools are not bulky or compact and are passed without straining. It is when bowel motions fall below 3 per week that it meets the medical diagnostic criteria for intestinal hypomobility / functional constipation, where the colon moves stool more slowly than it should. [5][6]

Bulky or Compact Stools

When stool remains in the colon for an extended period, excessive water is reabsorbed through the colonic mucosa, leading to progressively drier fecal matter. This desiccation results in compact, firm stools that may fragment into small, hard, pebble-like pieces, a pattern commonly associated with slow colonic transit and functional constipation. [2]

Straining during ≥10% of defecation attempts

Intestinal Hypomobility can be gauged by the proportion of bowel movements that require applying force / straining during defecation. Clinical diagnostics stipulate straining in under 10 - 25% of bowel motions indicates minimal constipation, 25 - 50% reflects frequent constipation, and over 50% denotes predominant to severe constipation. [2][57]

Defecation time exceeding 60 seconds

Clinical studies demonstrated that most healthy adults can pass the average stool within 60 seconds, with the mean average time for men being 44 seconds and a woman 56 seconds. Evacuation times exceeding 1 minute, and particularly those over 2 minutes, are considered prolonged and suggestive of a defecatory disorder including intestinal hypomobility. [55][56]

Sensation of incomplete evacuation 

In slow-transit constipation, the stool moves sluggishly through the colon. Even when some stool is passed, more may remain in the rectum or colon, making the evacuation feel incomplete. [57]

Abdominal distension / trapped gas 

In patients with slow colonic transit a reduced rate of fecal propulsion results in prolonged retention of intestinal contents. This stagnation permits excessive fermentation and gas accumulation, which becomes trapped, and subsequently contributes to significant bloating that results in abdominal distention. 

A prospective study involving over 2,000 patients with functional constipation found that over 90% reported experiencing bloated, and importantly, those with prolonged colonic transit exhibited greater abdominal distension compared with patients who had normal transit times [4][54]

Anal pain, burning or fresh blood

Straining over time during defecation generates repeated and excessive intrarectal pressure, which places mechanical stress on the anorectal tissues. This pressure can cause engorgement of the blood vessels in the anal canal leading to the development or worsening of hemorrhoids. Similarly, the passage of hard or bulky stool under force can cause tearing of the thin epithelial tissue of the anal canal, resulting in anal fissures. 

Clinically, these injuries may present with bright red blood on the stool surface or toilet paper, pain or burning and or itching during and after defecation, and in some cases mucous discharge due to overstretched tissue, which weakens local mucosal integrity. [52][53] 

Causes

Serotonin Deficiency 

On a molecular level, gut motility is a complex process that includes several layers of neural and hormonal control from the colon up to the central nervous system. On a simplified level, peristalsis, the major movement of the gut is mediated predominantly through the neurotransmitter serotonin (5HT).

When food or the stool distends the gut wall, enterochromaffin cells release 5HT. This causes a local reflex mediated through enteric nerves, releasing stimulating neurotransmitters such as acetylcholine, which cause muscle contractions behind the bolus [8].

Research has demonstrated 5HT is significantly lower in enteric neurons of those experiencing Intestinal Hypomobility, causing sluggish bowel motions, and that supplementation with 5HT supported neurological activities necessary for motility [9],[10],[11].  

Hypothyroidism

A study on 366 participants with hypothyroidism demonstrated the following correlation with constipation:

• 50% experienced constipation [58]

Constipation is among the most common gastrointestinal symptoms of hypothyroidism, primarily caused by reduced intestinal peristalsis due to a deficiency of T3, which normally promotes smooth muscle contractility in the gastrointestinal tract. It is reported up to 15% of hypothyroid patients have fewer than 3 bowel movements per week, combined with bloating and abdominal discomfort due to small intestinal bacterial overgrowth from hypomotility [59]

Chronic Stress [ SNS Hyperactivation ] 

The stress related hormone Noradrenaline suppresses gastrointestinal activity by inhibiting the release of acetylcholine, the principal excitatory neurotransmitter responsible for stimulating intestinal muscle contraction and promoting digestive secretions. As a result, digestive movement slows. This mechanism is designed to conserve energy during acute stress but chronic stress impairs bowel clearance [60]

Liver Insufficiency 

Liver Insufficiency prevents the liver from conjugating adequate amounts of bile from detoxification processes, and bile acids themselves act as laxatives. A study found people with chronic Intestinal Hypomobility had reduced bile acid synthesis and altered daily bile acid secretion compared to people with regular bowel movements[12]. Further, bile acids have also been found to promote NO synthesis in the epithelial cells suggesting another laxative mechanism [13].

Enzymatic Maldigestion

When the presence of food enters the small intestine, it results in the contractions of the smooth muscles. These alternate wave-like contractions in the intestine are called peristalsis.Peristalsis supports the mixing of food with digestive enzymes in order to metabolise food. Naturally the system supports the propulsion of food at a rate allowing proper digestion and absorption of foods, which is ordinarily a few millimetres per second. Various studies illustrate delayed gastric transit times in those with pancreatic insufficiency [14],[15].

Dysbiosis 

Gut microbiota dysbiosis in Intestinal Hypomobility are complex, but as an example it has been demonstrated that lower levels of Bifidobacteria contribute to Intestinal Hypomobility[16]. Potentially by promoting the production of short-chain fatty acids that positively impact intestinal transit. Several studies have also illustrated the positive effect on Intestinal Hypomobility with several probiotics detailed later. 

Dehydration

The colon receives approximately 1.5 L of liquid daily from the small intestine, with 200 mL to 400 mL excreted in the stool. The functions of the colon are to absorb fluid and transport waste to the rectum. Removal of water from the faecal slurry is time dependent and this time can be substantially increased in dehydrated states [17]. 

High-Fructose and High-Fat Diets

It has been illustrated in research that high-fat diets or high-fructose diets decrease defecation volume significantly and increase the levels of pro-inflammatory cytokines and metabolites by altering the microbiome and significantly lowering 5-HT, which results in reduced intestinal peristalsis [18]. 

Certain Conditions

• Type 1 and 2 Diabetes

• Multiple sclerosis

• Parkinsons

• Spinal cord injury [19]

Nerve damage 

Disruption of neural regulation of colonic motility plays a part in Intestinal Hypomobility. This loss of neural regulation may result from mechanical damage to pelvic nerves due to childbirth or pelvic surgery, or exposure to environmental toxins such as insecticides or heavy metals [20].

Medication

Another group of drugs frequently associated with Intestinal Hypomobility are antidepressants, especially tricyclic antidepressants. Analgesics, such as opiates and cannabinoids, are especially notorious for causing Intestinal Hypomobility. Anti-Parkinson, antiepileptic and antipsychotic drugs are also associated with Intestinal Hypomobility [21].