Research Paper: Ultrasonographic Comparison of Deep Lumbopelvic Muscles Activity in Plank Movements on Stable and Unstable Surface

Purpose: The body core facilitates the transition of forces and moments between the upper and lower extremities in every movement. The present study investigated the differences in the sonographic activity of the deep lumbopelvic muscles during the implementation of plank movements on stable and unstable surfaces. Methods: In total, 16 female athletes with the Mean±SD age of 23.69±3.57 years, Mean±SD height of 165.12±4.93 cm, and Mean±SD weight of 56.88±5.34 kg participated in this controlled laboratory study. Before the study onset, the Madison Model X8 ultrasound (Made in Korea) with Surface Linear Probe with the frequencies of 7.5 to 10.5 MHz was used to measure the thickness of the internal and external abdominal muscles, quadratus lumborum, and multifidus muscles. Moreover, their thickness was measured while performing front and side plank exercises on stable and unstable surfaces. The Paired Samples t-test was used for data analysis considering α=0.05. Results: There were no statistically significant differences in the mean diameter changes of the internal and external oblique, quadratus lumborum, and multifidus muscles in the front and side plank positions between the stable and unstable surfaces (P>0.05). Conclusion: Probably, the shift from stable to unstable position (using Swiss ball) does not change the level of deep core muscles’ activity in female athletes. Furthermore, exercising at each stable and unstable position may have no additional effects on these muscles.