While his wife, Hilaria , prefers dancing, Alec Baldwin was doing push-ups with the stars ... in the middle of a restaurant!

Check out the video ... Alec, 67, and his wife's former "Dancing with the Stars" pro partner, Gleb Savchenko , 42, square off in a pushup contest ... right in the middle of dinner.

And it looks like Alec's been keeping in shape ... a voice can be heard off camera, cheering, "C'mon, Gleb! You can't let him beat you again!"

It's unclear where the face-off went down ... Hilaria posted this battle for the ages on Instagram Monday night, captioning, "Actually can't take them anywhere. They do the male bonding."

Well, with eight children, he's gotta find time to workout somehow! Give 'em hell, Alec!

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