title: Surface electromyography activity of the rectus abdominis, internal oblique, and external oblique muscles during forced expiration in healthy adults.
abstract: We aimed to characterize rectus abdominis, internal oblique, and external oblique muscle activity in healthy adults under expiratory resistance using surface electromyography. We randomly assigned 42 healthy adult subjects to 3 groups: 30%, 20%, and 10% maximal expiratory intraoral pressure (PEmax). After measuring 100% PEmax and muscle activity during 100% PEmax, the activity and maximum voluntary contraction of each muscle during the assigned experimental condition were measured. At 100% PEmax, the external oblique (p<0.01) and internal oblique (p<0.01) showed significantly elevated activity compared with the rectus abdominis muscle. Furthermore, at 20% and 30% PEmax, the external oblique (p<0.05 and<0.01, respectively) and the internal oblique (p<0.05 and<0.01, respectively) showed significantly elevated activity compared with the rectus abdominis muscle. At 10% PEmax, no significant differences were observed in muscle activity. Although we observed no significant difference between 10% and 20% PEmax, activity during 30% PEmax was significantly greater than during 20% PEmax (external oblique: p<0.05; internal oblique: p<0.01). The abdominal oblique muscles are the most active during forced expiration. Moreover, 30% PEmax is the minimum intensity required to achieve significant, albeit very slight, muscle activity during expiratory resistance.
authors.affiliation: Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, Osaka, Japan. Electronic address: itok@rehab.osakafu-u.ac.jp.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Ito
authors.affiliation: Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, Osaka, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Nonaka
authors.affiliation: Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, Osaka, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Ogaya
authors.affiliation: Department of Physical Medicine and Rehabilitation, Kansai Electric Power Hospital, Osaka, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ogi
authors.affiliation: Department of Rehabilitation, Iwakuni Medical Center, Yamaguchi, Japan.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Matsunaka
authors.affiliation: Faculty of Health Sciences, Kyoto Tachibana University, Kyoto, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Horie
mesh_terms: D000071596:Abdominal Oblique Muscles / Q000502:physiology*; D000328:Adult; D064131:Back Muscles / Q000502:physiology; D004576:Electromyography; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D017568:Rectus Abdominis / Q000502:physiology*
keywords: Expiratory muscle training; External oblique muscle; Forced expiration; Internal oblique muscle; Rectus abdominis muscle; Surface electromyography