Zac Efron's former trainer hates burpees as much as you do. Here's why he says most people shouldn't do them.

• Burpees are common in workouts, but most people can't do them safely, a celebrity trainer told Insider.
• Patrick Murphy, who trained Zac Efron for "Baywatch," said her never programs them.

Burpees are not an efficient exercise and most people don't have the flexibility to perform them safely and properly, according to celebrity trainer Patrick Murphy.

Burpees are a full-body movement which involve dropping from a standing position straight into a squat, jumping the feet back into a high-plank position followed by a push-up, before jumping the feet forward, and jumping up again to repeat the process.

They're an explosive movement which raise the heart-rate, and were used to test fitness in the US military, Murphy told Insider.

Murphy, who has trained celebrities including Cameron Diaz, Jennifer Lawrence, and Zac Efron (for his famously shredded body in "Baywatch"), never includes burpees in his workouts because he believes they can lead to injury and a bad posture.

There are lots of other explosive exercises you can do that are much better, he said.

Burpees were used to test fitness levels in the military

The burpee was invented by exercise physiologist Royal Burpee in the 1930s, and it initially didn't include a push-up or a jump, as Insider's Hilary Brueck previously reported.

Royal Burpee's granddaughter, Sheryl Burpee Dluginski (who is also a personal trainer), told Men's Journal that the US army added them to a fitness test for soldiers, and made them into the more strenuous burpee we know today.

"It doesn't mean it's good for us or good for the human body," Murphy said.

Most people don't have the flexibility to perform a burpee correctly

To perform a burpee properly, you need a decent level of flexibility, strength, and fitness, Murphy said, and so they should only be performed by those who are fit enough.

The movement requires athleticism and quick movement, but when people try and move as fast as they can while being explosive, they're more likely to injure themselves, Murphy said.

"For most people, their shoulders will shrug, they'll hurt their wrists, they'll strain their back and their knees," he said.

Moving from the push-up to standing position in a burpee can create a rounded back, which is the posture many people spend all day in when working an office job — and can lead to back pain, Murphy said.

Burpees are really hard on the body for most people, he said.

"They're great for dodging bullets though," Murphy said. "If I was in the military, I would get good at burpees too."

Burpees raise the heart rate, but other exercises do the same thing more safely

Murphy isn't the only trainer to argue that burpees aren't effective for the majority of people.

Dluginski also told Insider that the burpee should be considered "an exercise for people who are already physically fit."

"It's really hard on the knees. It's really hard on the back. And unless you have good core strength and good fitness to start out with, you're not going to be able to do it correctly. That's exactly why it makes such a good fitness assessment test, which is what it really is," she said.

Fellow celebrity trainers and brothers Ryan and Eric Johnson, whose clients include Scarlett Johansson, previously told Insider that they think burpees are a waste of time for most people.

"Most people don't have adequate mobility to get into a deep squat, so they're going to flex their back," Eric said.

"In the bigger picture I don't believe that a burpee will have any sort of advantage that will make you hit your performance goals, other than getting your heart-rate up, and there are so many other tools to do that that will actually transfer over and help you in other facets of your training plan."

Squat jumps or box step-ups are great alternatives to the burpee for raising the heart-rate and building explosive power, Murphy said.