Carrie Underwood's simple workout routine

Carrie Underwood has a simple work out routine.

The 'Something in the Water' hitmaker has revealed the secret to her stunning figure, opting for running, squats and lunges to help her keep in shape.

Speaking to Entertainment Tonight at the American Country Countdown Awards on Sunday evening (01.05.16), she said: "You don't need that much. I like free weights and a Bosu, and you're in business. Maybe a medicine ball.

"I do lots of squats and lunges, and I like to run, I like to run outside if my knee allows me to. But just body weight stuff, push-ups, pull ups. It doesn't have to be complicated."

Meanwhile, the 33-year-old singer - who has 14-month-old son Isaiah with her husband, ice hockey star, Mike Fisher - previously revealed she thinks her "bum is a little nicer than it used to be" before she gave birth.

She shared: "I weigh more than I did when I was at my smallest, but I have a lot more muscle tone. I feel like my bum's a little nice than it used to be."

And Carrie has embraced her post-baby body, admitting having a child has also changed the "dynamic" of her marriage to the 35-year-old sportsman.

She added: "Your marriage does change a lot when you have a baby. It's a whole new dynamic.

"If we could keep having babies like Isaiah, we'd probably have quite a few. I would love to have a girl.

"I feel like everybody expected me to have an album full of 13 mommy-and-me tracks. Like, everything would be sentimental and mushy. I'm still me, and this is just another layer. I don't want to lose myself in being a mom."