Abstract
[Purpose] The purpose of this study was to verify the differences between sthenometry of the hip flexor muscles in trunk fixation with both arms or the contralateral lower extremity and without trunk fixation. [Subjects] In this study, 20 healthy subjects (10 male, 10 females; aged 19 to 33) participated after we obtained their informed consent. [Methods] We measured the hip flexor muscles strength using a hand-held dynamometer, and recorded electromyograms around the trunk and hip. We compared hip flexion isometric strength and electromyograms in three postures: 1) trunk fixation with both arms, 2) trunk fixation with the contralateral lower extremity, 3) without trunk fixation. [Results] Isometric hip flexor strength without trunk fixation was lower than that in the trunk fixation with both arms or the contralateral lower extremity. In trunk fixation with both arms, external abdominal obliqus and paraspinalis muscle activities were higher than without trunk fixation. Moreover, in trunk fixation with the contralateral lower extremity, the hip flexor and biceps femoris muscles activities were also higher than without trunk fixation. [Conclusion] The results demonstrate that trunk fixation enhanced hip flexor muscles strength because muscle activity rose due to posture maintenance.
