Britney Spears has posted an intense workout video to Instagram in which she focusses on both cardio and muscle-building exercises while showing off her killer abs - much to the delight of her dedicated followers.

In the clip, Spears can be seen doing crunches on an ab machine, running on a treadmill, lifting weights, using a medicine ball, and doing squats.

As indicated by the caption, Spears aims to be able to fit in her skinny jeans. "Skinny jeans, here I come," she writes.

She also says at the start of the video: "OK, so winter is coming and I need to get in my skinny jeans so I’m going to be on the treadmill today for 20 minutes and then after that, I’m going to do abs and focus on getting a six-pack. So here I go."

The workout video was generally well-received by fans of the ...Baby One More Time hitmaker, many of whom felt inspired by the upload.

One fan praised Spears, calling her the "multitasking queen of neck exercising during each workout."

"My favorite fitness instructor! Can you please make a new album of songs that we can all do your workouts to??? Does anybody else want this or nah?" a different fan asked.

"I did 1000 sit-ups everyday the summer before 8th grade because that’s what you did. You Brit. A true fitness icon," wrote a third.

However, not everyone was as impressed by the singer's efforts, with many commenting on the fact that she had not washed off her makeup for the workout.

"I wish I had all day to film myself in a mansion, work out, oh...and clearly never shower or shampoo or wash make up off...yea..I want that life!" one critic wrote.

"I just want to use make up remover on her eyes," another added.

Britney Spears has posted an intense workout video to Instagram in which she focusses on both cardio and muscle-building exercises while showing off her killer abs - much to the delight of her dedicated followers.

In the clip, Spears can be seen doing crunches on an ab machine, running on a treadmill, lifting weights, using a medicine ball, and doing squats.

As indicated by the caption, Spears aims to be able to fit in her skinny jeans. "Skinny jeans, here I come," she writes.

She also says at the start of the video: "OK, so winter is coming and I need to get in my skinny jeans so I’m going to be on the treadmill today for 20 minutes and then after that, I’m going to do abs and focus on getting a six-pack. So here I go."

The workout video was generally well-received by fans of the ...Baby One More Time hitmaker, many of whom felt inspired by the upload.

One fan praised Spears, calling her the "multitasking queen of neck exercising during each workout."

"My favorite fitness instructor! Can you please make a new album of songs that we can all do your workouts to??? Does anybody else want this or nah?" a different fan asked.

"I did 1000 sit-ups everyday the summer before 8th grade because that’s what you did. You Brit. A true fitness icon," wrote a third.

However, not everyone was as impressed by the singer's efforts, with many commenting on the fact that she had not washed off her makeup for the workout.

"I wish I had all day to film myself in a mansion, work out, oh...and clearly never shower or shampoo or wash make up off...yea..I want that life!" one critic wrote.

"I just want to use make up remover on her eyes," another added.