The effects of changes in support and inclined boards on lower-extremity muscle activity

[Purpose] The purpose of this study was to identify the effects of changes in support and inclined boards on lower-extremity muscle activity. [Subjects and Methods] The study subjects were 15 healthy adult males. Aero-Step equipment was used as an unstable support, and an inclined board was used to maintain angles of 0° and 20°. Electromyography was employed to analyze lower-extremity muscle activity. [Results] The vastus lateralis, vastus medialis, rectus femoris, gastrocnemius, soleus, and tibialis anterior muscles showed significant differences according to changes in the support and inclined board. In post-hoc tests the vastus lateralis, vastus medialis, and rectus femoris muscles showed significantly increased activity when exercises were performed on the unstable inclined board (20°) than the stable support (0°), unstable support (0°), or stable inclined board (20°). The gastrocnemius, soleus, and tibialis anterior muscles showed significantly increased activity when exercises were performed on the unstable support (0°), stable inclined board (20°), or unstable inclined board (20°) than on the stable support (0°). [Conclusion] An unstable support and increased slope of the inclined board may increase lower-extremity muscle activity.