noun
knee-swing mount; legging-up
A gymnastics move on the horizontal bar where the gymnast swings a leg over the bar to mount it. The term 'legging-up' is a less common English equivalent.
体操の授業で、足掛け上がりの練習をした。
In gymnastics class, we practiced the knee-swing mount.
Compound of 足掛け (あしかけ, 'leg hook' or 'knee swing') and 上がり (あがり, 'mounting' or 'getting up'), describing the action of mounting the bar by swinging a leg over it.