title: Abdominal breathing increases tear secretion in healthy women.
abstract: OBJECTIVE
  To determine the relationship between abdominal breathing and tear meniscus volume in healthy women, we investigated the change in tear meniscus volume in two groups: normal breathing and abdominal breathing.
  
  
  METHODS
  We used a crossover experimental model and examined 20 healthy women aged 20-54 years (mean ± SD, 32.7 ± 11.1 years). The participants were randomly assigned to one of two groups. During the first visit, the normal breathing group was subjected to normal breathing for 3 min, whereas the abdominal breathing group was subjected to abdominal breathing (4-second inhalation and 6-second exhalation) for 3 min. During the second visit, the protocols were swapped between the two groups. We estimated the R wave to R wave (R-R) interval, tear meniscus volume, salivary amylase activity, pulse, and blood pressure before and immediately after, 15 min after, and 30 min after completion of the breathing activity.
  
  
  RESULTS
  After abdominal breathing, compared to that before breathing, the tear meniscus volume increased significantly 15 min after breathing (P<.01). Furthermore, systolic blood pressure showed a significant decrease immediately after abdominal breathing (P<0.05). No significant difference was found in the test parameters in the normal breathing group.
  
  
  CONCLUSIONS
  Abdominal breathing for 3 minutes increases the tear meniscus volume in healthy women. Consequently, abdominal breathing may be considered in the treatment of dry eye disease.
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Kokoro
authors.initials: K
authors.lastname: Sano
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan. Electronic address: motoko-k@a3.keio.jp.
authors.forename: Motoko
authors.initials: M
authors.lastname: Kawashima
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ikeura
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Arita
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tsubota
mesh_terms: D000005:Abdomen / Q000502:physiology*; D000328:Adult; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D012016:Reference Values; D015656:Respiratory Mechanics / Q000502:physiology*; D013666:Tears / Q000378:metabolism*; D055815:Young Adult
keywords: abdominal breathing; parasympathetic nervous system; strip meniscometry; tear meniscus volume; visual display terminal (VDT)