on the balls of his feet

"The House of Silk" からの引用です。

He was also wearing black gloves and a black bowler hat. From the way he was standing, poised on the balls of his feet. I expected him to whip out a tape measure at any moment.
"poised on the balls of his feet" の個所の意味が直ぐには連想できなかったのですが、以前(7/7/2017)に "walk on the balls of his feet" を調べたことを思い出しました。
"ball(also ball of the foot)" に "The rounded protuberant part of the foot at the base of the big toe."/"The rounded protuberant part of the hand at the base of the thumb."（Oxford English Dictionary）の意味があるのですが、犬や猫の肉球を連想をしてしまいますが、犬や猫の肉球は "ball" ではなく "paw" でしたね。