title: Influence of Body Position on Defecation in Humans.
abstract: OBJECTIVE
  To compare three positions for defecation by measuring abdominal pressure and the anorectal angle simultaneously.
  
  
  METHODS
  We recruited six healthy volunteers. The videomanometric measures included simultaneous fluoroscopic images, abdominal pressures, subtracted rectal pressures and anal sphincter pressures. Three positions were used: sitting, sitting with the hip flexing at 60 ° with respect to the rest of the body, and squatting with the hip flexing at 22.5 ° with respect to the rest of the body.
  
  
  RESULTS
  Basal abdominal pressure before defecation on hip-flex sitting was lower than that with normal sitting, although the difference did not reach statistical significance. Basal abdominal pressure before defecation on squatting (26 cmH2 O) was lower than that with normal sitting (P < 0.01). Abdominal pressure increase (strain) on hip-flex sitting was lower than that with normal sitting, although this difference did not reach statistical significance. Similarly, the abdominal pressure increase on squatting was smaller than that with normal sitting, and yet the difference did not reach statistical significance. The rectoanal angle on defecation on hip-flex sitting did not differ from that with normal sitting. The rectoanal angle on defecation on squatting (126 °) was larger than that with normal sitting (100 °) (P < 0.05), and was also larger than that with hip-flex sitting (99 °) (P < 0.01).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Internal Medicine, Division of Neurology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Urology, Tokyo Women's Medical University, Tokyo, JapanAishin Seiki Inc., Tokyo, JapanClinical Physiology Unit, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Radiology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Neurology, Chiba University, Chiba, JapanDepartment of Urology, Dokkyo Medical College, Tochigi, Japan.
authors.forename: Ryuji
authors.initials: R
authors.lastname: Sakakibara
authors.affiliation: Department of Internal Medicine, Division of Neurology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Urology, Tokyo Women's Medical University, Tokyo, JapanAishin Seiki Inc., Tokyo, JapanClinical Physiology Unit, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Radiology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Neurology, Chiba University, Chiba, JapanDepartment of Urology, Dokkyo Medical College, Tochigi, Japan.
authors.forename: Kuniko
authors.initials: K
authors.lastname: Tsunoyama
authors.affiliation: Department of Internal Medicine, Division of Neurology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Urology, Tokyo Women's Medical University, Tokyo, JapanAishin Seiki Inc., Tokyo, JapanClinical Physiology Unit, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Radiology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Neurology, Chiba University, Chiba, JapanDepartment of Urology, Dokkyo Medical College, Tochigi, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Hosoi
authors.affiliation: Department of Internal Medicine, Division of Neurology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Urology, Tokyo Women's Medical University, Tokyo, JapanAishin Seiki Inc., Tokyo, JapanClinical Physiology Unit, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Radiology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Neurology, Chiba University, Chiba, JapanDepartment of Urology, Dokkyo Medical College, Tochigi, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Takahashi
authors.affiliation: Department of Internal Medicine, Division of Neurology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Urology, Tokyo Women's Medical University, Tokyo, JapanAishin Seiki Inc., Tokyo, JapanClinical Physiology Unit, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Radiology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Neurology, Chiba University, Chiba, JapanDepartment of Urology, Dokkyo Medical College, Tochigi, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Sugiyama
authors.affiliation: Department of Internal Medicine, Division of Neurology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Urology, Tokyo Women's Medical University, Tokyo, JapanAishin Seiki Inc., Tokyo, JapanClinical Physiology Unit, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Radiology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Neurology, Chiba University, Chiba, JapanDepartment of Urology, Dokkyo Medical College, Tochigi, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kishi
authors.affiliation: Department of Internal Medicine, Division of Neurology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Urology, Tokyo Women's Medical University, Tokyo, JapanAishin Seiki Inc., Tokyo, JapanClinical Physiology Unit, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Radiology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Neurology, Chiba University, Chiba, JapanDepartment of Urology, Dokkyo Medical College, Tochigi, Japan.
authors.forename: Emina
authors.initials: E
authors.lastname: Ogawa
authors.affiliation: Department of Internal Medicine, Division of Neurology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Urology, Tokyo Women's Medical University, Tokyo, JapanAishin Seiki Inc., Tokyo, JapanClinical Physiology Unit, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Radiology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Neurology, Chiba University, Chiba, JapanDepartment of Urology, Dokkyo Medical College, Tochigi, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Terada
authors.affiliation: Department of Internal Medicine, Division of Neurology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Urology, Tokyo Women's Medical University, Tokyo, JapanAishin Seiki Inc., Tokyo, JapanClinical Physiology Unit, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Radiology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Neurology, Chiba University, Chiba, JapanDepartment of Urology, Dokkyo Medical College, Tochigi, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Uchiyama
authors.affiliation: Department of Internal Medicine, Division of Neurology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Urology, Tokyo Women's Medical University, Tokyo, JapanAishin Seiki Inc., Tokyo, JapanClinical Physiology Unit, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Radiology, Sakura Medical Center, Toho University, Sakura, JapanDepartment of Neurology, Chiba University, Chiba, JapanDepartment of Urology, Dokkyo Medical College, Tochigi, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Yamanishi
keywords: constipation; defecation; manometry; squatting