Modified Supine Bridge Alters Muscle Coordination Patterns

<p> <p id="x-x-JCL-P-1"> Contributions of mono- and bi-articular hip extensor muscles while performing single leg supine bridge (SLB) and modified single supine bridge (mSLB) is not quite clear. To identify hip extensor muscles activation patterns among different unilateral-bridges, could be a key point for hip extensor strength and rehabilitation trainings. <p id="x-x-JCL-P-2"> PURPOSE: To compare hip extensor muscles activation patterns during performing SLB and mSLB. <p id="x-x-JCL-P-3"> METHODS: We have recruited healthy collegiate students for the project. Participants signed an informed consent form before data collection. They have performed SLB and mSLB at a constant pace (~2s up and ~2s down). mSLB was performed unilaterally with the exercise leg placed up on a box of 40 cm in height. Surface electromyography (sEMG) of the right gluteus maximus (Gmax), biceps long head (BFL), and semitendinosus (STN) muscles was recorded using a wireless surface electromyography system. Peak RMS sEMG of each muscle during SLB define as 100% and used as the base of comparison with that of mSLB. On- and off-set of sEMG bursts threshold were defined as 10% of the peak value. One-tailed paried-test was used for statistic examination. Alpha value was set at 0.05. <p id="x-x-JCL-P-4"> RESULTS: The peak RMS of Gmax, BFL and STN sEMG while performing mSLB were 82.1&plusmn;21.4, 141.5&plusmn;36.4, and 155.0&plusmn;2.5, respectively. The peal magnitude of the hamstring muscle activations were greater, although peak Gmax activity was lower (p&lt;0.05), while performing mSLB than that of SLB (p&lt;0.05). Muscle activation burst duration of BFL was 1.6&plusmn;0.7s longer while performing mSLB than that of SLB (p&lt;0.05). Muscle activation burst durations of STN (3.82&plusmn;0.58s) and Gmax(3.53&plusmn;1.72s)were (0.42&plusmn;0.50s) and Gmax(0.47&plusmn;0.44s)shorter than that of mSLB (p&lt;0.05). <p id="x-x-JCL-P-5"> CONCLUSIONS: Comparing to SLB, mSLB increased bi-articular hip extensor (BFL and ST) muscle activation level while reduced mono-hip extensor (Gmax) activation level accompanied by prolonged BFL activities and shortened Gmax/St activation durations. </p> </p> </p> </p> </p></p>