Relationship between Impact Force of Fall and Activity of the Gluteus Medius Muscle during Fall Descent

Abstract

[Purpose] The purpose of this study was to evaluate the relationship between the impact force of fall and the activity of the gluteus medius muscle during fall descent. [Methods] Eleven healthy volunteers performed deliberate falls in 3 directions (lateral, posterolateral, posterior) on a force platform covered by a mattress of 13 cm thickness. Fall descent motions and impact postures were examined by a three-dimensional analyzer. The maximum ground force reaction and activity of the gluteus medius were measured. [Results] The impact forces were between 2000 and 4000 N. For each fall pattern, the activity of the gluteus medius muscle during fall was 20-40% of the activity during maximum contraction, without significant difference among the fall pattterns. The activity of the gluteus medius muscle exhibited positive correlations with the impact force in all directions of fall. [Conclusion] These results suggest that increases of the gluteus medius muscle activity during fall descent can lead to increased impact force on the ground.