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.—
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 defecation posture
The squatting 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.
Advantages and health benefits
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).
- 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
- 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.
- 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.
- Sikirov, B.A. (February 1989). "Primary constipation: an underlying mechanism". Med. Hypotheses 28 (2): 71–3. doi:10.1016/0306-9877(89)90016-9. PMID 2927355.
- Sikirov, B., A. (1988): Etiology and pathogenesis of diverticulosis coli: a new approach. Medical Hypotheses. May; 26(1): 17-20.
- Cho YK, Kim CS, Koo ES, Yun JW, Kim JW, Lee JH, Park CY, Sohn CI, Jeon WK, Kim BI, Choi DI (2003): Contribution of Posture to Anorectal Angle and Perineal Descent on Defecography in Korean J Gastroenterol, 2003 Mar; 41(3):190-195 (in Korean). Quote: "In patients with spastic pelvic floor syndrome, squatting position increases the anorectal angle" (from the abstract).
- Balukian, L. (2002): In praise of squatting in Altern-Ther-Health-Med, 2002 Jan-Feb; 8(1): 26