What episode was when inuyasha and his friends meets an old women that is exercise?

You're likely thinking of Episode 101 of Inuyasha, titled "The Mysterious Old Woman and the Mysterious Power."

In this episode, Inuyasha and his friends encounter an old woman who appears to be training with a large, heavy log. They soon learn that she is actually a powerful youkai called Shikon no Baba, who possesses the power to manipulate the Shikon no Tama (Jewel of Four Souls).

However, Shikon no Baba is a trickster who uses her power to manipulate others, leading to a hilarious and ultimately dangerous situation for Inuyasha and his friends.