The trainer who got Ryan Gosling Ken-worthy abs for 'Barbie' on why you should start workouts with core exercises

• David Higgins trained the cast of 'Barbie' and each workout started with core exercises.
• This engages the abdominal muscles and help you get the best from your workout.
• Higgins had the cast build their core strength with planks and a 9-minute circuit.

Do ab exercises at the beginning of your workout, not just at the end, if you want to see the best results, according to the personal trainer who worked with the cast of "Barbie," including Margot Robbie and Ryan Gosling.

David Higgins, who is based in London, told Insider that he got the cast to engage their cores at the start of every workout.

"I'm from a pilates background so for me, engaging the core is everything at the beginning of the workout," Higgins said.

Activating the core muscles at the start means they will fire up throughout the rest of the workout, which not only is important for injury prevention but also means better results, he said.

"It's more about longevity and injury prevention rather than anything aesthetic, but the aesthetic value definitely comes because you're targeting it so specifically and then integrating it into everything that we do," Higgins said.

Don't leave core exercises until the end of a workout

Personal trainer Luke Worthington agrees, and previously told Insider that leaving core exercises until the end of a workout is a mistake.

You don't want to fatigue and annihilate your mid-section at the start, but rather activate the muscles with light work, such as bodyweight dead bugs, to prime the body for what it's about to do, he said.

When it comes to actually training the core and building the abdominal muscles later in your workout, this requires working harder, adding load, higher reps, and progressive overload to fatigue the muscles, he said.

The 'Barbie' cast did planks and 9-minute core circuits

Higgins said he helped the "Barbie" cast strengthen their core muscles with a 9-minute bodyweight workout.

However, they also performed regular planks, which are isometric holds and require the whole body to be engaged.

At one point, the cast did a plank challenge, which Margot Robbie won — beating Gosling by over a minute. She held a plank for four minutes and 10 seconds, while he clocked in at three minutes and two seconds.

"The plank is a specific exercise that requires a bit more control, stability, posture, just to get the most to maximize your efforts, it's a very easy exercise to get wrong," Higgins said. "To learn how to do it correctly is really important, what I would advise is to start nice and slow, start on your elbows and knees, and hold a neutral spine. Engaging your core is really very important — you don't want the exercise to be going to your lower back."

Higgins recommends starting with a 20-second plank on your knees then resting for 10 seconds. Slowly build that up, increasing the plank time until you can lift your knees off the floor and hold a full plank.

"You can make it more challenging by coming up on your hands or lowering yourself to your elbows," Higgins said. "And you can do it anywhere, you don't need any equipment — on your hotel room floor, in the kitchen, on the beach."