Motherhood is not slowing tennis G.O.A.T. Serena Williams down ... squats with a weighted bar on her shoulders, a lifting workout that targets the lower back, glutes, and hamstrings.

Serena Williams' baby daughter Adira is taking after her sporty mom! "We all work out in this family," Williams, who is married to Reddit cofounder Alexis Ohanian, captioned a new Instagram video ...