Purpose: The purpose of this study is to investigate the effects of healthy persons performing a plank exercise with hip abduction and use of sling on trunk muscle activity. Methods: Twenty-three subjects participated in this study. Muscle activities of the multifidus, rectus abdominis, external oblique and internal oblique were assessed with electromyography (EMG) while the subjects performed 6 various types of plank exercises in random order.Results: There was a significant difference in multifidus and internal oblique on the supported side and the multifidus, external oblique, and internal oblique on the elevated side (p< 0.05), and differences in plank methods were significantly higher in the multifidus, rectus abdominis, external oblique, internal oblique of the supported side and the rectus abdominis, external oblique and internal oblique on the elevated side (p< 0.05). In addition, post-hoc analysis of the various plank methods showed that muscle activity was significantly higher during the general plank exercise compared with the knee-supported-in-sling plank exercises (p < 0.05), and was significantly higher with the ankle-supported-in-sling plank exercises compared with the general plank exercise. Conclusion: There was greater trunk muscle activity with plank exercises performed with the ankle-supported-in-sling and hip abduction plank exercises compared with the general or knee-supported-in-sling plank exercises. Through this study, various plank exercises have been discovered that can be selected at different intensities for core muscle training purposes based on trunk muscle strength.

Objective: To investigate the effect of performing three different toe touch (TT) task condition on the activities of four different muscles using surface electromyography (sEMG) in healthy young adults. Design: Cross-sectional study. Methods: A total of 20 healthy young adults (6 males, 14 females) voluntarily participated in this study. All subject randomly performed three different TT task conditions as follows: general toe-touch (GTT) task, one side toe touch (TT) task during weight bearing, and one side foward toe touch (FTT) task during weight bearing. The muscle activities of erector spinae (ES), gluteus maximus (GM), hamstring (HAM), tibialis anterior (TA) muscles during the TT task were measured using sEMG. Subject performed each of the three conditions three time in random order and mean values were obtained. Results: With the trunk flexion period, the TT and FTT showed significantly greater muscle activity in the GM, HAM and TA compared to the GTT task (p<0.05). The TT position showed significantly greater HAM muscle activity than the GTT position. The dominant and nondominant ES muscle activity was significantly greater in the FTT compared to the GTT position (p<0.05). The dominant GM, HAM, and TA was significantly greater in the TT and FTT compared to the GTT position (p<0.05). Although the dominant ES was significantly greater in the TT and FTT compared to the GTT position (p<0.05), the dominant GM muscle activity was signifcantly greater in the TT compared with the GTT position (p<0.05). Conclusions: These findings may be applicable within the clinical field for selective trunk and lower extremity muscle activation and basic biomechanics purpose.

The purpose of this study was to investigate the conditions for the application of various plank exercises to people who require trunk stabilization by comparing trunk muscle activity according to the degree of hip abduction in the plank exercise. Design: Cross-sectional study. Methods: Twenty healthy participants voluntarily participated in this study and the plank exercise was performed under 5 conditions (two-legged support plank [TSP] with hip abduction, TSP with hip abduction of 15 degrees, TSP with hip abduction of 30, one-legged support plank [OSP] with hip abduction of 15 degrees, OSP with hip abduction of 30 degrees). In order to measure the trunk muscle activity according to the 5 conditions, surface electromyography was used. The electrical activities of the rectus abdominis (RA), external oblique (EO), and internal oblique (IO) muscles were measured during the 5 plank exercises. Subjects practiced each of the 5 conditions three times in random order and the average values were obtained. Results: In the OSP condition with 15/30 degrees of hip abduction, activities of the RA, EO, and IO were significantly greater than during the TSP (p<0.05). In the OSP with 30 degrees of hip abduction condition, activities of the left EO, IO were significantly greater than other plank exercise conditions (p<0.05). Conclusions: The plank exercise with hip abduction of 30 degrees and the OSP exercise can be suggested as an effective method to enhance the activity of the trunk oblique muscles.

Objective: The purpose of this study was to compare the effects of performing squats and kneeling squats on trunk and lower extremity muscle activity in persons with stroke.Design: Cross-sectional study. Methods: Ten persons with stroke (3 male and 7 female) were recruited. The subjects were instructed to randomly perform the 4 different squat conditions: squat with 30 degrees of knee flexion, squat with 60 degrees of knee flexion, squat with 90 degree of knee flexion, and the kneeling squat. During the squat performance, surface electromyograms (sEMG) was used to assess muscle activity of the erector spinae (ES), gluteus maximus (Gmax), gluteus medius (Gmed), and biceps femoris (BF) muscles. Results: Muscle activation of the ES and BF were significantly increased with the kneeling squats compared to the general squats with 30 degrees and 60 degrees of knee flexion (p<0.05), and muscle activation of the Gmax and Gmed were significantly increased with the kneeling squats compared to all other squat conditions (p<0.05). Conclusions:The results suggest that the kneeling squat is an effective exercise to strengthen the proximal muscles of the lower extremities. Rather than applying a difficult general squat to the stroke population, the kneeling squat may be applied as a safer method for training the proximal muscles.