Humans mainly use one of two types of defecation postures to defecate: either squatting or sitting. People use the squatting posture when using squat toilets or when defecating in the open in the absence of toilets. The sitting posture on the other hand is used in toilets that have a pedestal or "throne", where users generally lean forward or sit at 90-degrees to a toilet seat.
In general, the posture chosen is largely a cultural decision and is determined by early childhood habits. However, it may also be dictated by the available toilet type, as a squat toilet can only be used in a squatting position, whereas squatting on a toilet designed for sitting is not recommended. When people are travelling to different countries, they may therefore be forced to use a different defecation posture than what they are used to or prefer.
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 developing countries although this changing in some countries where a shift from squatting to sitting is being observed. Toilet seats are a recent development, only coming into widespread use in the nineteenth century.
The sitting position has some advantages: It 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. It is therefore often the preferred position of people with disabilities and elderly people.
The squatting defecation posture involves squatting, or crouching. It requires standing with knees and hips sharply bent and the buttocks close to the ground. Squat toilets and toilet squat stools are designed to facilitate this posture. They are more widespread in developing countries than elsewhere, particularly in those with a Muslim or Hindu majority. Anal cleansing with water, which is practised by most Muslims due to the Islamic toilet etiquette might be easier to do from a squatting position than from a sitting position.
The sitting position causes the defecating human to assume a narrow anorectal angle, which may be obstructive and causes difficulty in emptying the bowels. The sitting position can cause the defecating human to repeat the Valsalva maneuver many times and with great force; this may overload the cardiovascular system and cause defecation syncope. Research comparing the length of time needed to defecate using various postures found that the sitting defecation posture requires "excessive expulsive effort compared to the squatting posture". It has been aruged that squatting is "the only natural defecation posture".
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