Effects of Pelvic Floor Muscle Contraction on Abdominal Muscle Activity and Pelvic Rotation Angle during Active Straight Leg Raise: Cross-Sectional Study

Background Active straight leg raise (ASLR) has been used to assess the functional ability to transfer loads through the pelvis and different motor control strategies of transversus abdominis. The pelvic floor muscles are also an important part of the local muscle system. Purpose To investigate the relationships among pelvic floor muscle contraction (PFMC), abdominal muscle activity, and the pelvic transverse rotation angle during voluntary PFMC in healthy, continent women. Study design Cross-sectional study Methods 16 continent women were instructed to perform ASLR with and without PFMC. PFMC was confirmed by transabdominal ultrasound. Surface electromyography data were collected from the muscle activities of the transversus abdominis/internal oblique (TrA/IO), external oblique (EO), and multifidus, and the pelvic rotation angle was measured using a smartphone-based measurement tool. The results were analyzed using the paired t-test (α=0.05). Results PFMC led to an increased both TrA/IO (p<0.01) and decreased contralateral EO muscle activation (p<0.01), together with a greater decrease in pelvic rotation angle (p<0.001), during ASLR. Conclusions The ASLR with PFMC method may be effective for individuals with pelvic floor dysfunction, which cause unwanted pelvic rotation and decreased TrA/IO muscle activity.