Former World No.1 Serena Williams may have hung up her racket, but the WTA legend is still aiming to stay in shape, despite being pregnant with her second child.

The 41-year old is expecting her second child with husband Alexis Ohanian, and posted a video showing her working out while sporting a very noticeable baby bump.

The 23-time Grand Slam champion posted a video on Youtube, where she was seen working out. Williams elaborated on the difficulty of having a strict training regimen, while pointing out specific pain and nuances she experienced during the exercise.

"I'm very active with this stretch just to feel it open up and this is kind of pathetic because my hips are insanely tight," said Williams. "I have more range of motion on this side for whatever reason my left is so tight, and honestly, the baby is literally sitting on my nerve. So it's more on the left, which makes it even more tight."