Lady Gaga "had a blast" on her birthday while spending quality time with her close family and friends.

The pop songstress turned 26 on Wednesday and opted to keep celebrations low-key.

Gaga, who is currently preparing for her upcoming international concert tour, ditched discotheques in favour of a cycling class at the gym with her closest kin.

"She requested [Bruce Springsteen's] Thunder Road [at the gym] because it's one of her favourite songs," a source told Us Weekly magazine. "Her friends filled the studio, and they had a blast."

After breaking a sweat, Gaga dashed back to her abode to eat a home-cooked meal prepared by her mum.

"It was just a small thing with her family," the source explained. "Her mother cooked."

Gaga's schedule has been jam-packed with rehearsals and other tour preparations recently.

The singer was happy to have some downtime on her special day.

"She's been ridiculously busy, and has been working herself very, very hard," another insider said. "But everyone had the most amazing time [yesterday]!"

Lady Gaga's Born This Way Ball tour will begin on April 27 in Seoul, South Korea.