Does defecating while sitting cause more strain than squatting?

Question

This commercial¹ from "Squatty Potty" claims that evacuating stool in a seated position is suboptimal for humans because we have a muscle that partially pinches the colon when seated. They claim that, due to our evolution, the colon only becomes unobstructed by this muscle when in a crouched position.

Using a Squatty Potty toilet stool can help with straining issues such as hemorrhoids, pelvic organ prolapse, constipation, bloating and IBS.

Does squatting prevent "straining issues"?

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^{1. It looks to me like they're really trying to sell a product and just using humor.}

Answer 1

Normal defecation is initiated by three components

(1) spontaneous phasic contractions of rectum starting during filling.

(2) smooth muscle relaxation of the anal canal with an increased recto-anal angle.

(3) application of voluntary expulsive force as straining.

Process of Defecation: Research shows that the defecation is a complex, learned process which requires both an intact nervous system and normal muscle function.

Defecation starts when the cerebral cortex receives an awareness and perception of critical level of filling in the rectum. When the individual adopts a sitting or squatting position, the anal sphincters and the puborectalis relax, straightening the anorectal angle. Simultaneously, the voluntary efforts of bearing down increases the intra-abdominal pressure, facilitating the development of a stripping wave, resulting in stool evacuation.

Attempting to voluntarily control defecation often results in straining per Pierre Paré, in 2011

This action should be as simple a manoeuvre as breathing because defecation is a complex phenomenon that starts with the desire initiated by rectal distension, followed by anal relaxation, appropriate descent of the pelvic floor, and expulsatory action by the pelvic and abdominal musculature.

The protective effects of squatting against constipation are not backed up by clinical data per Dr. Darren Brenner, a gastroenterology specialist. Further when inquired about Squatty Potty's claims by Eric Spitznagel,

"If you're a normal healthy person, I don't know if it's going to change anything in the short term or the long term," he said. "Maybe by changing your position, in 20 or 30 years down the line you'll reduce your likelihood of developing constipation. But there's no data to suggest that whatsoever."

Rebekah Kim a colorectal surgeon at the Center for Pelvic Floor Disorders at Virginia Hospital Center said in NPR that there are no clinical studies proving squatting reduces the amount of straining on the toilet.

"Squatting on a stool can reduce the amount of straining on the toilet, which may mean less hemorrhoids, but there are no clinical studies proving that," she says.

Research also shows that chronic constipation caused by straining (one of the Rome III criteria for constipation) may lead to complications such as hemorrhoids and anal fissure. The research evidence for body postures (squatting or sitting) in relation to straining is presented below.

1. Straining issues: Research by Sikirov D in 2003 in twenty-eight healthy volunteers (ages 17–66 years) showed that more effort was required to defecate in the sitting position compared to the squatting position.

In conclusion, the present study confirmed that sensation of satisfactory bowel emptying in sitting defecation posture necessitates excessive expulsive effort compared to the squatting posture.

2. Body position: Research by Ryuji Sakakibara et.al. in 2010 compared three positions for human defecation by measurement of the anorectal angle and abdominal pressure simultaneously in six healthy volunteers. They found that squatting straightened the anorectal angle and there was less force required to defecate.

Conclusion: The results of the present study suggest that the greater the hip flexion achieved by squatting, the straighter the rectoanal canal will be, and accordingly, less strain will be required for defecation.

3. Anal fissure: Straining constitutes the most important factor leading to the development of anal fissure. Research by Imtiaz Ahmed et.al. in 2013 shows that modified commode squatting posture has the highest success rate for the treatment of chronic anal fissure.

Conclusion: Our results clearly conclude that by simply changing posture of defecation and keeping in view the anatomical angle formed during this posture not only cures but also prevents the occurrence of anal fissure in first hand and can save the patient from lot of agony, pain and loss of their industrial hours.

4. Hemorrhoid: The question of the efficacy of squatting as a way of preventing or curing haemorrhoids remains to be resolved per Christine Dimmer in 1996.

Squatting deserves considerably more attention before it is rejected as an option.

5. Colorectal cancer: A study by Sahand Sohrabi et.al. in 2012 did not support an appreciable role for using sitting toilets as risk factors for CRC.

In conclusion, our study did not support an appreciable role for using sitting toilets as risk factors for CRC. Further larger prospective studies are needed to confirm this finding.

6. Functional constipation: Research by Fahrul Azmi Tanjung et.al. in 2013 shows that posture during defecation correlates with functional constipation in children.

Our study revealed that functional constipation was more likely happened in children with sitting (12/20) rather than squatting posture (4/45) during defecation. Previous studies explained that defecation in a squatting posture requires a shorter time and less effort compared to a sitting posture. Also, the squatting posture creates lower intraabdominal pressure than the sitting posture.

Limitations of squatting: Research shows a small rise in blood pressure in healthy and hypertensive patients adopting squatting posture and it has been been suggested that people with hypertension or higher risk of stroke should avoid it.

Search process for the research listed above

1. Databases used-NCBI, Google
2. Search terms used-'defecation posture', 'squatting defecation'
3. Hits obtained-NCBI-7,22, Google-numerous
4. Exclusion/Inclusion criteria-19 papers were irrelevant to the claim or did not meet the necessary information required in the question in NCBI and were excluded. Studies comparing defecation postures and straining were eligible for inclusion.

Referring to the advise from the chronic constipation patient leaflet of the World gastroenterology organization which has representation from 100 member societies with over 50,000 individual gastroenterologists worldwide, mimicing the natural position of squat may help bowel movements,

Sitting differently on the toilet may help your bowel movements. The natural position is a ‘squat’, which is not practical on most toilets. To mimic this position, try raising your feet with a footstool by around 25cm (10in), keep them flat and hip width apart, and lean forwards on your thighs and relax.