Flush toilets are meant to be used with the user comfortably seated on them, but some medical researchers claim this posture is associated with health risks
Humans can defecate in a number of defecation postures. The two most common are the squatting defecation posture and the sitting defecation posture. The squatting posture is used for squat toilets; it is also commonly used for defecation in the absence of toilets or other devices. The sitting defecation posture is used in Western toilets, with a lean-forward posture or a 90-degrees posture. In general, the posture chosen is largely a cultural decision. The defecation posture chosen by an individual may affect certain medical conditions, such as defecation syncope (fainting while defecating), as well as urination.
Some authors believe that the anorectal angle (ARA), the angle formed by the junction of the rectum with the anus, is "one of the most important contributions to anal continence"; its normal value at rest is 90 degrees.
According to a 1996 article in the Townsend Letter for Doctors and Patients,
In a classic paper, Tagart (1966) measured the anorectal angle in various postures, finding that the angle is partially straightened out when squatting. He argued that squatting thereby reduced the pressure required for defecation and recommended a hips-flexed position for defecation to help treat constipation and prevent haemorrhoids.
The sitting defecation posture involves sitting with hips and knees at approximately right angles, as on a chair. Most Western-style flush toilets are designed to be used with a sitting posture. The sitting posture is more widespread in the Western world, and less common in the developing world. Toilet seats are a recent development, only coming into widespread use in the nineteenth century.
Advantages and health benefits
The sitting position helps protect privacy and leaves little or no chance of getting fecal matter on clothes or ankles. It may feel more comfortable as it can minimize strain in thighs, calves, ankles and lower back. Breathing is also easier while sitting than squatting.
Disadvantages and health risks
The sitting position causes the defecating human to assume a narrow anorectal angle, which some people believe is obstructive and causes difficulty in emptying the bowels. Critics of this posture say that squatting is "the only natural defecation posture".
The sitting position can cause the defecating human to repeat the Valsalva maneuver many times and with great force, which may overload the cardiovascular system and cause defecation syncope. Sikirov also published 2004 study in which he compared the length of time needed to defecate using various postures, and concluded that the sitting defecation posture requires "excessive expulsive effort compared to the squatting posture".
A sitting posture may increase diverticulosis of the colon. The magnitude of straining during defecation is at least three times greater than with the squatting posture.
Squatting defecation posture
Some toilets allow the user to defecate in either the squatting or the sitting position
The squatting defecation posture involves squatting by standing with knees and hips sharply bent and the buttocks suspended near the ground. Squat toilets are designed to facilitate this posture. It is more widespread in the developing world than in the Western world. In the US, the squatting position is colloquially known as the "catcher's position" or the "catcher's posture" because of its similarity to the posture that baseball players must maintain while playing the catcher position.
^ALTOMARE Donato F.; RINALDI Marcella; VEGLIA Antonella; GUGLIELMI Altomarino; SALLUSTIO Pier Luca; TRIPOLI Gaetano (Department of Emergency and Organ Transplantation, General Surgery and Liver Transplantation Units, Coloproctology Unit, University School of Medicine, Bari, ITALY) (2001): Contribution of posture to the maintenance of anal continence, in International journal of colorectal disease, 2001, vol. 16, number 1, pp. 51-54 (4 ref.). Publisher: Springer.
^Christine Dimmer, Brian Martin, Noeline Reeves and Frances Sullivan , "Squatting for the Prevention of Hemorrhoids?", Published in Townsend Letter for Doctors & Patients, 1996: 159, 66-70 link
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^Sikirov, Dov, MD (1990): "Cardio-vascular events at defecation: are they unavoidable?" Medical Hypotheses, 1990, Jul; 32(3): 231-3.
^A History of Technology, Vol.IV: The Industrial Revolution, 1750-1850. (C. Singer, E Holmyard, A Hall, T. Williams eds) Oxford Clarendon Press, pp. 507-508, 1958.