BACKGROUND: This study aimed to determine whether trunk stability muscles co-contract with body position as a factor of pelvic floor muscle (PFM) activity.

MATERIAL AND METHODS: Sixty-one healthy adults without pelvic floor dysfunction were examined for pelvic floor and trunk stability muscle activity in 4 body positions (ankle dorsiflexion and plantar flexion in standing position, and ankle dorsiflexion and plantar flexion in long sitting position). The activities of the PFMs via anal/vaginal probes, internal oblique (IO), multifidus (MF), tibialis anterior, and gastrocnemius muscles were measured by surface electromyography. Three-dimensional motion analysis measured the movement of the pelvis in real time according to the change in body position.

RESULTS: There was a significant increase in PFM activity from the ankle neutral position while standing for both ankle dorsiflexion and plantar flexion in standing position (p < 0.05). In maximal contraction of PFM in the standing position, IO and MF were found to co-activate (p < 0.05).

CONCLUSIONS: In standing position, the ankle dorsiflexion and plantar flexion positions activated PFMs, which was found to co-activate with trunk stability muscles. Pelvic floor training programs based on the results of this study may be helpful in patients with incontinence.

Keywords: Electromyography, Imaging, Three-Dimensional, Pelvic Floor, Posture, Urinary Incontinence, Anal Canal, Ankle, Ankle Joint, Movement, Muscle Contraction, Muscle, Skeletal, Vagina