[Purpose] This study compared the activities of the abdominal and hip extensor muscles between the bridging exercise (BE) and bridging exercise with hip adduction (BEHA) positions in women using electromyography (EMG). [Subjects] We recruited 14 healthy adult females with no history of low back pain. [Methods] The subjects performed bridging exercises with and without hip adduction. The EMG activities of the rectus abdominis (RA), external oblique (EO), internal oblique (IO), and gluteus maximus (GM) muscles were recorded. [Result] The EMG activities of all muscles were significantly increased during the BEHA compared to the BE. [Conclusion] The bridging exercise with hip adduction produced greater activation of the abdominal and hip extensor muscles.

[Purpose] The purpose of this study was to compare the relative levels of activation of the gluteus medius (Gmed) and rectus femoris (RF) muscles during natural (N) sit-to-stand (STS) and STS with hip abduction (ABD) in young and elderly females. [Subjects] We recruited 15 healthy young females and 15 healthy elderly females. [Methods] The activities of the dominant lower extremity gluteus medius (Gmed) and rectus femoris (RF) muscles were measured using a wireless electromyography (EMG) system for natural STS and STS with hip abduction. [Result] In the elderly subjects, the Gmed increased significantly and RF decreased significantly when STS was performed with hip ABD compared with when it was performed naturally. The Gmed in the elderly subjects was significantly increased during natural STS compared with in the young subjects. [Conclusion] These results indicate that the Gmed was recruited to compensate for weakened RF muscle function in the elderly adults.

[Purpose] The purpose of this study was to compare the activation of the tibialis anterior (TA) and soleus (SOL) muscles during the sit-to-stand (STS) task with hip adduction and hip abduction in elderly females. [Subjects] We recruited 16 healthy elderly females with no pain in the knee joint and no other orthopedic problems of the lower limbs. [Methods] The activities of the dominant lower extremity muscles were measured using a wireless electromyography (EMG) system. Subjects then performed a total of nine STS trials, including three trials each for hip adduction, hip abduction, and natural STS tasks. [Results] In the pre- thigh-off (TO) phase, the normalized EMG data of the TA muscle increased significantly when the STS task was performed with hip adduction compared with hip abduction. In the post-TO phase, the normalized EMG data of the TA muscle showed a significant increase during the STS task with hip adduction compared with hip abduction. Additionally, the normalized EMG data of the SOL muscle increased significantly when the STS task was performed with hip adduction compared with hip abduction. [Conclusion] Therefore, the STS movement with hip adduction poses a greater challenge for balance control, indicating that certain elderly individuals would have difficulty in executing an abrupt adjustment in their dynamic postural stability during the STS movement.

| Abstract |1 )PURPOSE: The purpose of this study was to investigate the effects of isometric upper limb contraction on the trunk and lower extremity muscles during the sit-to-stand activity in elderly females. METHODS:Eighteen healthy elderly females performed three directional isometric upper extremity contractions (flexion, extension, and horizontal abduction movements) using an elastic band during sit-to-stand activity. Electromyography signals were collected from the internal oblique, erector spinae, rectus femoris, and biceps femoris muscles. RESULTS:Internal oblique activity was greater in bilateral shoulder flexion and bilateral shoulder horizontal abduction than in neutral position (p<.05). Erector spinae and rectus femoris muscle activities in bilateral shoulder flexion was greater than in neutral position and bilateral shoulder extension (p<.05). Biceps femoris activity was significantly greater in bilateral shoulder flexion than in bilateral shoulder extension and horizontal abduction, and in neutral position compared to bilateral shoulder extension (p<.05). †Corresponding Author : kmh211@inje.ac.kr This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. CONCLUSION:These results suggest that incorporating isometric upper limb contraction may be beneficial for enhancing the contribution of trunk and lower extremity muscle activities to trunk stabilization during sit-to-stand activity.Therefore, isometric upper limb contraction during sit-to-stand tasks, especially in flexion, may be used to elicit contraction of the lumbopelvic region muscles within a tolerable range, for developing endurance and strength in the elderly.

[Purpose] The purpose of this study was to compare the activation of the gluteus medius (Gmed), rectus femoris (RF), and biceps femoris (BF) muscles during neutral (N) sit to stand (STS) and STS involving hip abduction (ABD) in elderly females. [Subjects] We recruited 16 healthy elderly females with no pain in the knee joint or any other orthopedic problems of the lower limbs. [Methods] The activities of the dominant lower extremity muscles were measured using a wireless electromyography (EMG) system. Subjects then undertook a total of six STS trials: three for neutral STS and three for STS involving hip abduction. [Results] In the pre-TO phase, activation of the RF muscle was significantly increased during hip ABD. In the post-TO phase during hip ABD, Gmed muscle activation was significantly increased, and RF muscle activation was significantly decreased. [Conclusion] This study suggests that STS involving hip ABD is more effective in decreasing Gmed activation and reducing RF effort in elderly females.