The purpose of this study is to examine the effects of bridging exercises performed with different knee-joint angles on static and dynamic balance, and changes in muscle activity between before and after the exercises; it ultimately looks to present more effective bridging exercise methods. A total of 54 healthy staff members and students at Yongin-si’s O Hospital and Y University, respectively, were selected as the subjects of this study. The subjects were divided into three knee-joint angle groups of 18 members each (60°, 90°, 120°), and both static balance (EO C90A-Eye Open COP 90 Area, EC C90A-Eye Closed COP 90 Area, EO TL- Eye Open Trace Length, EC TL-Eye Closed Trace Length) and dynamic balance (forward, backward, leftward, rightward) were measured. Before dynamic balance was measured, EMG was attached (IO?internal oblique, EO?external oblique, ES?elector spinae, GM-glutes maxiums, TA-tibialis anterior and GCM-gastrocnemius) to measure muscle activity and dynamic balance simultaneously. After being measured before the exercise, the values were re?measured after the subjects performed bridging exercises five times repeatedly for 10 s each, five times a week for two weeks, at the various individual angles. The results of the study are as follows.
(1) Among static balance items, EO C90A showed significant differences between before and after the exercises at 60° and 90°; EC C90A showed significant differences at 60°, 90°, and 120°; EO TL showed significant differences at 60° and 90°; and EC TL showed significant differences at 60°, 90°, and 120°(p < 0.05). However, there were no significant differences among the angles.
(2) Among dynamic balance items, the forward direction showed significant differences between before and after the exercises, as well as among the various angles (p < 0.05).
(3) With regard to EMG values, during forward movements, IO, EO, TA, and GCM each showed significant differences between before and after exercise at 60° and 90°(p < 0.05); only IO showed significant differences among the various angles (p < 0.05).
(4) During backward movements, IO and EO each showed significant differences at 60° and 90°, and TA and GCM showed significant differences at all angles, between before and after exercises (p < 0.05); only EO showed significant differences among various angles (p < 0.05).
(5) During leftward movements, IO showed significant differences at 60° and 90°; EO, ES, and TA showed significant differences at all angles; and GCM showed significant differences only at 90°, between before and after exercise (p < 0.05). However, there were no significant differences among the angles.
(6) During rightward movements, IO showed significant differences at 90°; EO and ES showed significant differences at 90° and 120°; TA showed significant differences at 60° and 90°; and GCM showed significant differences at all angles, between before and after exercise (p < 0.05). However, there were no significant differences among the angles.
Therefore, bridging exercises at knee-joint angles of 60°, 90°, and 120° were effective. However, performing the exercise at 90° is considered to have the most significant effect.