訓 あし ・ 音 ソク
Sino-Vietnamese: túc
The top part is the knee and the bottom is 止 (a foot planted): the whole leg from knee down. It also carries the sense of "enough".
Stroke data: KanjiVG (CC BY-SA 3.0) — kanjivg.tagaini.net
足が痛いです。 (あしがいたいです)
My leg hurts.