Gabrielle Union sparked a major reaction from her social media followers this weekend as she posed up a storm in a string bikini.

MORE: Gabrielle Union rocks summer outfit of dreams at Miami Grand Prix

The actress and singer took to Instagram to share a sensational video of herself that left fans in awe over her incredible gym-honed figure. Soundtracked to Beyonce'sI'm That Girl, Gabrielle took a refreshing shower onboard a yacht. Referencing the song and her age, she captioned the post: "That Girl… Is 49."