Comparison of gluteus maximus muscle activity according to three different foot heights from the ground during bridge exercise

<b>Background:</b> Gluteus maximus (GM) and biceps femoris (BF) have important roles in the stability and mobility of the hip joint during various functional activities including bridge exercises. In addition, the different heights of the foot during bridge exercise can contribute to the other muscle activities of the lower extremities. <b>Objective:</b> This study aims to investigate the muscle activities of GM, BF, and multifidus (MF) during bridge exercises based on three different foot heights in healthy individuals. <b>Methods:</b> Fifteen healthy subjects were participated. An electromyography device was used to measure muscle activities of GM, MF, and BF. The participants were asked to perform bridge exercises with their feet at three different heights (0 cm, 5 cm, and 10 cm) from the ground in a random order. <b>Results:</b> The muscle activity of GM was significantly different among three conditions (the foot heights 0 cm, 5 cm, and 10 cm) (adjusted p-value [P_adj] < 0.01). The GM muscle showed higher activity with a foot height of 10 cm compared to 0 cm and 5 cm (P_adj< 0.01). Both MF muscles showed higher activity with a foot height of 10 cm compared to 0 cm (P_adj< 0.01). BF muscle showed lower activity with a foot height of 10 cm compared to 0 cm (P_adj< 0.01). The ratio of GM/BF muscle activity was higher during the bridge exercise with a foot height of 10 cm than with 0 cm and 5 cm (P_adj< 0.01). <b>Conclusion:</b> Bridge exercise at 30° of hip abduction with a foot height of 10 cm can be recommended to selectively facilitate GM and MF muscle activity and improve the muscle activity ratio of the GM/BF.