The Role of the Obturator Internus Muscle in Pelvic Floor Function

Tuttle, Lori J. PT, PhD; DeLozier, Elizabeth R. SPT; Harter, Kimberly A. SPT; Johnson, Stephanie A. SPT; Plotts, Christine N. SPT; Swartz, Jessica L. SPT

Journal of Women's Health Physical Therapy: January/April 2016 - Volume 40 - Issue 1 - p 15–19
doi: 10.1097/JWH.0000000000000043
Research Report

Objective: To investigate the effects of obturator internus (OI) strengthening on pelvic floor muscle (PFM) strength and hip external rotation (ER) strength.

Study Design: Randomized controlled trial.

Background: Rehabilitation strategies for pelvic floor disorders include PFM strengthening, but often this is not sufficient. Muscles surrounding the PFM (specifically, the OI due to a shared fascial attachment with the PFM) may play an important role in normal function and provide a target for rehabilitation that is more amenable to strengthening.

Methods and Measures: Forty nulliparous women 18 to 35 years old were randomly assigned to an exercise group (EX) or a control group (CON). The EX group completed an exercise program targeting strengthening of the OI muscle (hip ER). The EX group performed 3 sets of 10 repetitions of each exercise 3 times per week for 12 weeks. The CON group participated in testing sessions. ER strength (dynamometer peak force measure) and PFM strength based on Peritron (Laborie Medical, Ontario, Canada) peak vaginal squeeze pressure were measured. Separate repeated-measures analysis of variance was used with α= .05 to compare ER strength and vaginal pressure for each group after 12 weeks. Results are mean ± SEM.

Results: The EX and CON groups were not different at initial assessment in age, ER strength, or PFM strength (P > .05). The EX group showed increased peak pressure (24.21 ± 3.72 vs 35.43 ± 3.13 cm H2O; P < .05) and ER strength (16.44 ± 1.1 lb vs 19.95 ± 0.69 lb; P < .05). The CON group did not show change in peak pressure (32.16 ± 3.54 cm H2O vs 27.37 ± 2.5 cm H2O; P > .05) or ER strength (17.36 ± 0.54 lb vs 17.45 ± 0.65 lb; P > .05).

Conclusion: Strengthening of muscles surrounding PFM such as the OI could improve PFM strength (peak pressure) in nulliparous women, indicating that muscles other than the pelvic floor may be appropriate for rehabilitation.

Doctor of Physical Therapy Program, School of Exercise and Nutritional Sciences, San Diego State University, San Diego, California.

There are no conflicts of interest to declare.

Copyright © 2016 by the Section on Women's Health, American Physical Therapy Association.