Side-To-Side Difference in Electromyographic Activity of Abdominal Muscles during Asymmetric Exercises.

A side-to-side difference in the muscle size of the rectus abdominis has been suggested to increase the strain injury risk. Attenuating the difference in size of the rectus abdominis may decrease the injury risk. To explore ways to highly activate one side of the rectus abdominis, we aimed to clarify the activity levels of both sides of the muscle during asymmetric abdominal exercises. Fifteen male sprinters performed the following five asymmetric exercises for the right and left sides: (i) sit-up twist, (ii) oblique leg raise, (iii) side bridge, (iv) side bridge roll out with the elbow, and (v) side bridge roll out with the foot. Side bridge roll out with the elbow and that with the foot were performed using a wheeled platform. During the exercises, electromyographic signals were recorded bilaterally from the upper, central, and lower portions of the rectus abdominis. We calculated the root mean square of electromyograms during the concentric and eccentric phases of the exercises and normalized to that during maximal voluntary contractions. In all portions of the rectus abdominis, the root mean squares of electromyograms were significantly higher in the moving side than in the non-moving side during the concentric and eccentric phases of the side bridge, the side bridge roll out with the elbow and that with the foot (all p < 0.01), but not in sit-up twist or oblique leg raise. The root mean squares of electromyograms of all portions of the rectus abdominis in the moving side were significantly higher in the side bridge roll out with the elbow and that with the foot than in the side bridge during both phases (all p < 0.01). The results suggest that the application of the wheeled platform to side bridge is useful to highly activate one side of the rectus abdominis.

Side-to-side supercharging nerve allograft enhances neurotrophic potential.

INTRODUCTION: Critical limitations of processed acellular nerve allograft (PNA) are linked to Schwann cell function. Side-to-side bridge grafting may enhance PNA neurotrophic potential. METHODS: Sprague-Dawley rats underwent tibial nerve transection and immediate repair with 20-mm PNA (n = 33) or isograft (ISO; n = 9) or 40-mm PNA (n = 33) or ISO (n = 9). Processed acellular nerve allograft groups received zero, one, or three side-to-side bridge grafts between the peroneal nerve and graft. Muscle weight, force generation, and nerve histomorphology were tested 20 weeks after repair. Selected animals underwent neuron back labeling with fluorescent dyes. RESULTS: Inner axon diameters, g-ratios, and axon counts were smaller in the distal vs proximal aspect of each graft (P < .05). Schwann cell counts were greater, with a lower proportion of senescent cells for groups with bridges (P < .05). Retrograde labeling demonstrated that 6.6% to 17.7% of reinnervating neurons were from the peroneal pool. DISCUSSION: Bridge grafting positively influenced muscle recovery and Schwann cell counts and senescence after long PNA nerve reconstruction.

An electromyographical comparison of torso muscle activity and ratio during modified side bridge exercises.

BACKGROUND: Individualized exercise programs based on personal impairment could lead to successful rehabilitation. An effective way to train spine stability is to find exercises that take advantage of the synergistic relation between local and global stabilization systems. OBJECTIVE: This study aimed to investigate synergistic relationship between the muscles of the local and global systems during three modified side bridge exercises compared with traditional side bridge (TSB). METHODS: Twenty healthy participants performed TSB, both leg lift while side-lying (BLLS), torso lift on a 45∘ bench while side-lying (TLBS), and pelvic lift on side-lying (PLS) in random order. Surface electromyography data were analyzed. RESULTS: The results indicate that PLS was effective as TSB on trunk muscle activity. However, BLLS and TLBS demonstrated significantly less rectus abdominal (RA) muscle activity compared to TSB (p< .001). Additionally, BLLS and TLBS had a higher internal oblique (IO)/RA muscle activity ratio than TSB (p< .001). CONCLUSIONS: PLS could be a suitable alternative exercise for individuals who are unable to perform TSB, as it can effectively activate trunk muscles. BLLS and TLBS may be appropriate for training the local stability system, while limiting activation of the RA.

Trunk muscle endurance in Chinese adults.

BACKGROUND: Previous studies in non-Chinese populations have found a relationship between performance on isometric trunk muscle endurance tests and low back pain (LBP). However, the relationship between trunk muscle endurance and LBP in Chinese populations has received little attention and age-referenced data have not been reported. OBJECTIVE: Evaluate the relationship between age-referenced isometric trunk muscle endurance values and LBP in a Chinese cohort. METHODS: One hundred and eighty-eight participants (20-59-years) performed four timed-endurance tests (Biering-Sørensen, plank, left/right side bridge) in random order. Participants with a history of LBP completed an Oswestry Disability Index (ODI) and pain scale. Holding-times for the four tests were summed and receiver operating characteristic (ROC) curve analysis was performed to differentiate participants with and without LBP. RESULTS: Data were grouped by age. Analysis revealed similar endurance values to those reported in non-Chinese populations, except longer holding times were recorded in the 50-59 yr Chinese cohort. Pain scores were positively correlated with ODI scores. ROC curve analysis showed that the area under the curve was 0.723 and optimal cut-off was 288 sec (sensitivity and specificity both 0.75). CONCLUSIONS: This study is the first to describe trunk muscle endurance reference data in Chinese people. Individuals with a summed endurance time of < 288 seconds appear more likely to suffer LBP.

Relationship between scapular muscle and core endurance in healthy subjects.

BACKGROUND: Scapular muscle endurance and core endurance reportedly influence shoulder injury risk. The exact relationship between scapular muscle endurance and core endurance, and how they impact one another in the healthy subjects remain unclear. OBJECTIVE: To investigate the relationship between scapular muscle endurance and core endurance in healthy subjects. METHODS: Fifty healthy volunteers (23 males, 27 females; mean age 20.42 ± 1.04 years) were participated in this study. Endurance of the serratus anterior and trapezius muscles was assessed using the scapular muscle endurance test. Sorensen test (endurance of trunk extensor muscles), trunk flexor endurance test, and side bridge test (endurance of lateral core muscles) were conducted to assess the core endurance. Pearson's product moment correlations examined relationships between scapular muscle endurance and each of the core endurance tests scores. RESULTS: Scapular muscle endurance test scores showed a positive correlation with the side bridge test scores (r = 0.414; p = 0.003). No significant correlation was found between scapular muscle endurance test scores and the other core endurance tests scores (p > 0.05). CONCLUSIONS: There appears to be a link between the scapular muscle endurance and lateral core muscles in healthy subjects; however, more research is needed to provide a definitive answer on the nature of this relationship. Further studies involving patients with shoulder pathology are warranted.

Evaluation of Relationship between Trunk Muscle Endurance and Static Balance in Male Students.

PURPOSE: Fatigue of trunk muscle contributes to spinal instability over strenuous and prolonged physical tasks and therefore may lead to injury, however from a performance perspective, relation between endurance efficient core muscles and optimal balance control has not been well-known. The purpose of this study was to examine the relationship of trunk muscle endurance and static balance. METHODS: Fifty male students inhabitant of Tehran university dormitory (age 23.9±2.4, height 173.0±4.5 weight 70.7±6.3) took part in the study. Trunk muscle endurance was assessed using Sørensen test of trunk extensor endurance, trunk flexor endurance test, side bridge endurance test and static balance was measured using single-limb stance test. A multiple linear regression analysis was applied to test if the trunk muscle endurance measures significantly predicted the static balance. RESULTS: There were positive correlations between static balance level and trunk flexor, extensor and lateral endurance measures (Pearson correlation test, r=0.80 and P<0.001; r=0.71 and P<0.001; r=0.84 and P<0.001, respectively). According to multiple regression analysis for variables predicting static balance, the linear combination of trunk muscle endurance measures was significantly related to the static balance (F (3,46) = 66.60, P<0.001). Endurance of trunk flexor, extensor and lateral muscles were significantly associated with the static balance level. The regression model which included these factors had the sample multiple correlation coefficient of 0.902, indicating that approximately 81% of the variance of the static balance is explained by the model. CONCLUSION: There is a significant relationship between trunk muscle endurance and static balance.