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.
Sitting defecation posture
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".
Squatting or crouching defecation posture
Squatting or crouching defecation posture involves squatting by standing with knees and hips sharply bent and the buttocks suspended near the ground. Squat toilets and toilet squat stools 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.
Defecation postures in space
- A. Rane; A. Corstiaans (2008, Department of Urogynaecology, Townsville Hospital, Townsville, Queensland, Australia): Does micturition improve in the squatting position? in Journal of Obstetrics and Gynaecology, Volume 28, Issue 3 of April 2008, pages 317 - 319. Quotes: "Posture on the toilet is an important consideration during micturition", "the ability to squat in our population of volunteers was quite poor" (from the abstract).
- Murad-Regadas, S. M.; Regadas, F. S. P.; Barreto, R. G. L.; Rodrigues, L. V.; De Souza, M. H. L. P. (October 2009). "A novel two-dimensional dynamic anal ultrasonography technique to assess anismus comparing with three-dimensional echodefecography". Colorectal Dis 11 (8): 872–7. doi:10.1111/j.1463-1318.2009.02018.x. PMID 19681980.
- Chu, Winnie C.W.; Tam, Yuk-him; Lam, Wynnie W.M.; Ng, Alex W.H.; Sit, Frances; Yeung, Chung-Kwong (May 2007). "Dynamic MR assessment of the anorectal angle and puborectalis muscle in pediatric patients with anismus: technique and feasibility". J Magn Reson Imaging 25 (5): 1067–72. doi:10.1002/jmri.20914. PMID 17410575.
- Murad-Regadas, S. M.; Regadas, F. S. P.; Rodrigues, L. V.; Souza, M. H. L. P.; Lima, D. M. R.; Silva, F. R. S.; Filho, F. S. P. R. (February 2007). "A novel procedure to assess anismus using three-dimensional dynamic anal ultrasonography". Colorectal Dis 9 (2): 159–65. doi:10.1111/j.1463-1318.2006.01157.x. PMID 17223941.
- Sikirov, Dov, MD (1990): "Cardio-vascular events at defecation: are they unavoidable?" Medical Hypotheses, 1990, Jul; 32(3): 231-3. PubMed
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- Balukian, L. (2002): In praise of squatting in Altern-Ther-Health-Med, 2002 Jan-Feb; 8(1): 26