First lady Michelle Obama said her "[tennis] skills are very questionable," but that didn't stop her from playing doubles against Serena Williams and hitting a 55 mph serve.

Mrs. Obama visited the US Open on Friday and spoke to local children about the importance of physical activity at a United States Tennis Association (USTA) Let's Move! event. Let's Move! is the first lady's campaign against childhood obesity.

She mentioned she started playing tennis after law school because there weren't many courts in the south side of Chicago where she grew up.

Has this sport contributed to her famous, toned arms?

ACE is a proud supporter of the Let's Move Campaign.

[via AP and Politico]