Jordin Sparks routines are so energetic they leave her "drenched" with sweat. The "Battlefield" singer - who shot to fame after winning U.S. TV talent show "American Idol" in 2007 - credits her support slot on The Jonas Brothers' tour for helping her lose weight.
She explained: "I'm literally drenched every night when I get off the set because the stage for this world tour I'm on is so massive. I'm constantly moving."
"I do have my trainer out on tour with me this time around. He just got here last week, and it's been a lot of fun. Any time I find time - or I'm not sleeping - he's like, 'Let's work out, let's do something.' I'm like 'nooo,' but he gets my butt up and I've got to do it. It's fun to do that."
The 19-year-old star does enjoy exercising, but admits her trainer works her so hard she aches.
She added to America's OK! magazine: "He doesn't keep the same thing every time, so he shocks the body so you're running, you're doing throw-downs, you're doing stairs, you're doing lunges. I've done all of those in the past four days, and I will tell you that my butt hurts very badly."