Rihanna's early workouts

Rihanna ensures she stays in shape by sticking to a punishing exercise regime - and she often hits the gym before dawn.

The Umbrella hitmaker is famed for her skimpy stage outfits, and her personal trainer, Ary Nunez, reveals the singer is so dedicated to keeping in shape, she regularly rises in the middle of the night for a workout.

She tells Britain's Star magazine, "Rihanna trains as much as she can, whenever she can. This could be every day or three times a week. Her work schedule is extremely demanding, so thank goodness she's naturally a hard-working person.

"We make time and find time - whether it is at 4am or 9am. We always squeeze it in."