Physical therapists who treat patients with urinary incontinence commonly utilize sEMG biofeedback. Practitioners compare resting tone, maximal contraction, and muscle endurance measures before and after pelvic floor exercise instruction to determine intervention and demonstrate progress. There is little research that supports the use of biofeedback in positions other than supine. The purpose of this study was to examine the effect of positioning on pelvic floor muscle activity as measured by surface electromyography (sEMG) in supine, sitting, and standing. Subjects were healthy nulliparous and multiparous women, 23-74 years old, with no symptoms, history, diagnosis, or treatment of incontinence. Subjects were randomized for exposure to sEMG in three different positions. Their age, parity, and delivery type was recorded. The subjects underwent a manual pelvic floor muscle strength assessment (PFMSA) to evaluate contraction recruitment. Then, using a vaginal probe electrode, they were instructed in a sEMG protocol which assessed baseline resting tone, maximal voluntary contraction, 10 second contractions, and a contraction-relaxation series in each of the three positions. Evaluation of resting tone both as an isolated measure and as part of a contraction-relaxation series was demonstrated to be higher in standing and sitting than in supine. A contraction trial lasting 10 seconds also demonstrated higher standing and sitting values. No differences were found between single maximal contraction or contraction in a contract-relax series between the three positions. Positions of standing and sitting respectively increase the resting tone and muscle recruitment demand of the pelvic floor as measured by sEMG when compared to supine. Physical therapists using sEMG to treat patients with pelvic floor weakness or laxity can anticipate that in positions other than supine, the pelvic floor support requirements increase.

Key Words: Measurement, pelvic floor muscles, position, supine, sitting, standing, sEMG, Normals

LLU Discipline

Physical Therapy


Physical Therapy Sciences


School of Allied Health Professions

First Advisor

Everett Lohman III

Second Advisor

Bonnie Forrester

Third Advisor

Gail Polvoorde

Fourth Advisor

Shannon Stegmaier

Degree Name

Doctor of Physical Therapy (DPT)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Physical Therapy; Pelvic Floor; Urinary Incontinence



Page Count

vi; 41

Digital Format


Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


Loma Linda University Electronic Theses and Dissertations

Collection Website



Loma Linda University. Del E. Webb Memorial Library. University Archives