[Purpose] The purpose of this study was to evaluate the effect of modified cervical exercise and determine whether such exercise improves the range of motion of the cervical movement in smartphone users with forward head posture. [Subjects and Methods] Some 32 subjects with forward head posture participated in this study. They were randomly allocated to three groups, and the modified cervical exercises were performed either once, twice, or three times per day. The exercise program was followed for four weeks and then the joint range of motion of the participants was measured. [Results] A significantly increased range of motion was seen in all three groups that performed the modified cervical exercises. The analysis of the effects among the three groups indicated that the greatest effect was seen in Group C, members of which performed the modified exercises three times per day. In addition, a significant difference was found between Group A and Group C in terms of the inter-group results. [Conclusion] According to the results of this study, although the modified cervical exercises were performed for only a relatively short duration (four weeks), the exercises brought about an improvement in the forward head posture that was induced by using a smartphone.

[Purpose] The purpose of this study was to examine the effects of different types of bridging exercises on the activities of the trunk muscles. [Methods] Twenty-four students participated in this experiment. The activities of the internal oblique (IO), external oblique (EO), rectus abdominis (RA), and erector spinae (ES) muscles were measured in four different bridging exercises. [Results] There were significant differences in the IO, EO, RA, and ES among the four kinds of bridging exercise. The activities of IO, EO and RA were the highest in prone bridging (exercise 4), followed by unilateral bridging (exercise 3), and supine bridging on balance pads (exercise 2). In conventional bridging (exercise 1), the activities of IO, EO, and RA were the lowest. The activity of ES was the highest in exercise 3 followed by exercises 2 and 1. The activity of ES was the lowest than in exercise 1. [Conclusions] Bridging exercise in the prone position may be a more effective method of enhancing trunk muscle activities exercises in other positions.

[Purpose] The purposes of this study were to strengthen gluteus maximus and trunk muscles depending upon the hip joint direction by bridging exercise on an unstable and stable surface, and to suggest an intervention method for efficient and selective exercise. [Participants and Methods] The test measured the muscle activities with the external rotation and internal rotation of 25 degrees and hip joint neutral position of 0 degree on a stable and unstable surface each exercise 3 times for 9 seconds. [Results] External oblique abdominis showed a higher muscle activity on the unstable surface and internal rotation. Erector spinae showed no significant difference on the surfaces and demonstrated the highest muscle activity at the internal rotation. Gluteus maximus showed a higher muscle activity on the stable surface and external rotation and the interaction effect between the surface and the angle indicated a statistical significance as well. [Conclusion] Muscle activities appear different depending upon the change of surface and joint angle, and it can be said that the correct mobilization of muscle fiber relying on the muscle arrangement direction and muscle contraction direction is the most important factor for gluteus maximus.

Objective: The purpose of this study is to compare the EMG activities of the trunk muscles when carrying a backpack with belts and without belts. Background: This research aimed to explore the influence of carrying a backpack with belts on the trunk muscles activity and to suggest a desirable method of wearing backpacks. Method: Seventy five adolescents participated in this study. The EMG activities of upper trapezious, cervical erector spinae and rectus abdominis were collected. One way ANOVA was used to analyze the collected data. LSD was used for post-hoc test. Results: The EMG data from treadmill walking showed significant differences between carrying a backpack with belts and without belts for the cervical erector spinae and upper trapezious(p<.05) in all group(A Group: no belt, B Group: lumbar belt, C Group: lumbar-chest belt). In descending walking, significant difference were found for the cervical erector spinae and rectus abdominis in all group. In ascending walking, there were no significant differences in all group. LSD showed that the muscle activity of the trunk muscles decreased significantly when the lumbar belt and lumbar-chest belt were worn. Conclusion: The trunk muscles activities were decreased when the subjects were wearing a backpack with belts, comparing with wearing a backpack without belts. Application: These results can be used to provide useful information on how wearing a backpack in adolescent.