Kim Kardashian's trainer reveals the key exercise that she never does

Kim Kardashian might be famous for the dramatic life her family leads and her saucy photos on Instagram, but there's nothing that catches the world's attention more than her curvaceous bod. Kim, a big fan of skin-tight dresses, tube tops and bike shorts (not to mention the aforementioned Instagram pics), has never been afraid to show off her assets.

But while her voluminous behind may have broken the internet a few times, you can't deny that Kim looks incredibly fit and healthy. I mean, you can see that those abs are genuinely there, with no photoshop or "sucking in" techniques evident.

And if you're wondering how long the 37-year-old spends on the treadmill to stay so tight and toned, you may be surprised to discover that she does barely any cardio at all.

Kim's trainer Melissa Alcantara revealed to Women's Health Mag that the mother-of-three hardly spends any time in the cardio section of the gym, and can usually be found lifting weights instead.

"We don’t go crazy on the cardio," Melissa said. "85 per cent of our training is weight training, and the other 15 is made up of cardio."

While it's a well-known fact that sweating it out doing cardio – aerobic exercise that significantly increases your heart rate – helps with weight loss and cardiovascular health, not many people know that doing only cardio probably won't get you where you want. Especially if you want a toned tummy and a peachy booty like Kim's.

Melissa explained that in a single week, she'll do weight training with Kim on six of those days. Depending on the day, sessions will last from an hour to an hour and 45 minutes, where they'll focus on different body groups including abs, legs and butt, chest and triceps, and back and biceps.

You might also be surprised to know that only two of those days are for leg and butt workouts. Although they're Kim's favourite, according to Melissa, the trainer insists that rest days to recover muscle groups are extremely important.

So what is that 15 per cent of cardio made up of?

"Two days out of the week we’ll do steady-state cardio," Melissa explained, "so just walking at a steady pace on the treadmill for usually around 20 minutes. Nothing getting the heart rate too high."

Huh, that doesn't sound too bad at all. But they do get the heart pumping a few times a week by increasing the intensity by doing 10 minutes of sprints. Melissa says Kim doesn't look forward to this part of her workout – but I don't think she's the only one.

"She hates sprints," Melissa revealed with a laugh. "But she does them still, no problem. She knows that the worst sh*t is the thing that works."

While that may be true, I know a lot of us think the "worst sh*t" is cardio, so finding out that Kim barely incorporates that into her workout routine is very good news indeed.