Co-contraction of Selected Core Muscles Performing Bridging Exercise with and without Instability Devices
Poster Presentation XML
1کارشناس ارشد بیومکانیک ورزشی، دانشکده تربیت بدنی و علوم ورزشی، دانشگاه خوارزمی تهران
2استاد، گروه بیومکانیک و آسیب شناسی ورزشی، دانشکده تربیت بدنی و علوم ورزشی، دانشگاه خوارزمی، تهران، ایران
3Assistant Professor of School of Physical Education and Sport Sciences, Shiraz University, Shiraz, Iran
Introduction: In numerous motor tasks, muscles around a joint act coactively to generate opposite torques which can be considered as an adoption of the limbs to changes in the environment. Recently, instability devices have become popular which are introduced to enhance the intensity of traditional exercises by decreasing stability. So, it seems that co-activation of muscles should be increased during instability training due to the reduction in stability but this assumption has not been investigated yet. The current study aimed to investigate differences in co-activation of selected core muscles (rectus abdominis (RA), external oblique (EO), erector spine lumbalis (ESL), and superficial lumbar multifidus (SLM)) over 5 seconds of bridging variations performed on stable and unstable surfaces.
Methodology: A total of 20 healthy active women participated in the study. Surface electromyographic data were collected on selected muscles while performing bridging exercise under stable (feet on the ground) and unstable conditions (feet on the Swiss ball and in the TRX ropes). Resulting muscle activation data was amplitude normalized and mean co-activation index values were calculated over a 3-s hold period of the workouts.
Results: Post-hoc analysis indicated that co-activation indexes of abdominal muscles were higher in all suspended conditions compared to the floor based bridging. The highest level of co- activation occurred in the foot suspended exercise using Swiss ball. Among four pairs of muscles investigated, RA- ES co-activation index was the greatest.
Discussion: Results of this study showed that bridging performed on an instability device may cause a greater challenge for core muscles and may lead to better results in core training programs. However, due to the increases in core muscles co-activation, individuals with a history of weakness in core region should be more cautious using instability devices.