The purpose of this study was to examine the effects of the flexion angle of the knee joint
and the abduction angle of the hip joint on the activation of the cervical region and abdominal muscles. [Subjects]
A total of 42 subjects were enrolled 9 males and 33 females. [Methods] The bridging exercise in this study was one
form of exercise with a knee joint flexion angle of 90°. Based on this, a bridging exercise was conducted at the postures
of abduction of the lower extremities at 0, 5, 10, and 15°. [Result] The changes in the knee joint angle and the
hip abduction angle exhibited statistically significant effects on the cervical erector spinae, adductor magnus, and
gluteus medius muscles. The abduction angles did not result in statistically significant effects on the upper trapezium,
erector spinae, external oblique, and rectus abdominis muscles. However, in relation to the knee joint angles,
during the bridging exercise, statistically significant results were exhibited. [Conclusion] When patients with both
cervical and back pain do a bridging exercise, widening the knee joint angle would reduce cervical and shoulder
muscle activity through minimal levels of abduction, permitting trunk muscle strengthening with reduced cervical
muscle activity. This method would be helpful for strengthening trunk muscles in a selective manner.
Key words: Bridging exercise, Knee and hip joint angle, Muscle activation