The stabilization of the trunk is necessary to increase spinal and pelvic stability in functional postures and movements, to strengthen the relevant muscles, and to recover control and balance of muscles and movements6). Abdominal muscle activity is an essential element in hip muscles, stabilization of the pelvis against pulling forces, and the forces on the trunk in state of pelvic stabilization are effectively delivered to the hip joints and lower extremities10). This study aimed to examine the influences of the knee joint angle and the hip abduction angle on the activation of the trunk, cervical, and abdominal muscles during a specific bridging exercise. To this end, electromyograms were recorded of seven muscles during bridging exercises with different according feet-to-hip length changes, i.e., changes of the knee joint angle with the hip in a neutral position without abduction of the lower extremities. The EMGs exhibited statistically significant changes in all the muscles. However, changes in muscle activity at different hip abduction angles during the bridging exercise showed statistically significant results only in the cervical erector spinae, adductor magnus, and gluteus medius muscles. These results indicate an increase in abdominal pressure due to the contraction of the abdominal muscles in accordance with changes in the knee joint angle. However, while abdominal muscle activity did not change during abduction, the muscles involved in pelvic abduction as well as the cervical and shoulder muscles, which served as a fixation point on the floor during the bridging exercise, exhibited increased activity.