title: Functional electrical stimulation to the abdominal wall muscles synchronized with the expiratory flow does not induce muscle fatigue.
abstract: [Purpose] Continuous electrical stimulation of abdominal wall muscles is known to induce mild muscle fatigue. However, it is not clear whether this is also true for functional electrical stimulation delivered only during the expiratory phase of breathing. This study aimed to examine whether or not intermittent electrical stimulation delivered to abdominal wall muscles induces muscle fatigue. [Subjects and Methods] The subjects were nine healthy adults. Abdominal electrical stimulation was applied for 1.5 seconds from the start of expiration and then turned off during inspiration. The electrodes were attached to both sides of the abdomen at the lower margin of the 12th rib. Abdominal electrical stimulation was delivered for 15 minutes with the subject in a seated position. Expiratory flow was measured during stimulus. Trunk flexor torque and electromyography activity were measured to evaluate abdominal muscle fatigue. [Results] The mean stimulation on/off ratio was 1:2.3. The declining rate of abdominal muscle torque was 61.1 ± 19.1% before stimulus and 56.5 ± 20.9% after stimulus, not significantly different. The declining rate of mean power frequency was 47.8 ± 11.7% before stimulus and 47.9 ± 10.2% after stimulus, not significantly different. [Conclusion] It was found that intermittent electrical stimulation to abdominal muscles synchronized with the expiratory would not induce muscle fatigue.
authors.affiliation: Department of Physical Therapy, Ibaraki Prefectural University of Health Sciences, Japan.
authors.forename: Yukako
authors.initials: Y
authors.lastname: Okuno
authors.affiliation: Department of Physical Therapy, Ibaraki Prefectural University of Health Sciences, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Takahashi
authors.affiliation: Graduate School of Health Sciences, Ibaraki Prefectural University of Health Sciences, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Sewa
authors.affiliation: Department of Internal Medicine, Ibaraki Prefectural University of Health Science Hospital, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Ohse
authors.affiliation: Department of Physical Therapy, Ibaraki Prefectural University of Health Sciences, Japan; Graduate School of Health Sciences, Ibaraki Prefectural University of Health Sciences, Japan.
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Imura
authors.affiliation: Department of Physical Therapy, Ibaraki Prefectural University of Health Sciences, Japan; Graduate School of Health Sciences, Ibaraki Prefectural University of Health Sciences, Japan.
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Tomita
keywords: Abdominal wall muscles; Functional electrical stimulation; Muscle fatigue