足(あし)が棒(ぼう)になるto have one's legs become stiff, tired

立(た)ち仕事(しごと)で足(あし)が棒(ぼう)になりました。

My legs have become stiff and tired from standing work. {to have one's legs become stiff, tired}

遊園(ゆうえん)地(ち)で一(いち)日(にち)中(じゅう)歩(ある)いたから足(あし)が棒(ぼう)になった。

My legs have become stiff because I walked around the amusement park all day. {to have one's legs become stiff, tired}

ずっと立(た)ちっぱなしだと足(あし)が棒(ぼう)になってしまいます。

"If you keep standing all the time, your legs will become stiff and tired." {to have one's legs become stiff, tired}

隣(となり)町(まち)まで歩(ある)いたら足(あし)が棒(ぼう)になったからマッサージに行(い)くつもりだ。

I'm planning to go for a massage because my legs became stiff from walking all the way to the neighboring town.

筋(きん)トレの成果(せいか)が出(で)てきたのか、足(あし)が棒(ぼう)になることが無(な)くなりました。

The results of my strength training seems to be showing, as my legs no longer become stiff or tired. {to have one's legs become stiff, tired}