Former Fittest Woman on Earth Katrin Davidsdottir keeps her core strong with exercises that include dead bugs and side planks.

• CrossFit player Catherine Davidsdottir has always had a six-pack, but her core wasn’t always strong.
• The former Fittest Woman on Earth said her heart’s neglect had resulted in a herniated disc.
• Davidsdottir now does several basic exercises, including deadbugs, side planks, and the L-sit load.

Catherine Davidsdottir does “a lot” of core exercises to maintain her status as an elite CrossFit player, including deadbugs, L-sit carry and bag carry, she told Insider.

The 29-year-old Icelandic athlete won CrossFit in 2015 and 2016, but she didn’t always prioritize her core — despite her visible abs.

“I’ve had a six-pack since I was a kid and it looks great, but that doesn’t always mean it’s working efficiently and your inner core is stable,” Davidsdottir told Insider.

While the abdominal muscles are the external muscles at the front of the torso, the core muscles include the abdominal muscles but also wrap around the entire middle portion and include the pelvis, diaphragm, lower back, and hips. The core helps stabilize the whole body, and you can have a strong core without a six-pack, or a six-pack without a strong core.

The former gymnast said one of her biggest mistakes was not doing enough core exercises, which resulted in a herniated disc at the end of 2019. A herniated disc, also known as a slipped disc, is where one of the soft tissue pads rests between the cushions. The bones of the spine move out of place.

Since then, Davidsdottir has made abdominal-strengthening exercises an essential part of her workout.

Katrin Davidsdottir does many different core exercises

To protect her back, Davidsdottir prioritized “McGill Big Three”: three basic exercises designed to be done before training, especially for people with back pain.

The exercises are:

Davidsdottir adds deadly bugs to this, another move that helps engage the core, personal trainer Luke Worthington previously told Insider.

Deadbugs, in addition to side planks, can help build abs, especially if you add weight, bodybuilder Hattie Boyd previously told Insider.

In 2021, Davidsdottir moved from the United States to Iceland to train with a new coach, Jami Tikkanen. Since making this change, she has incorporated more core exercises into her training.

A post shared by Katrín Tanja Davíðsdóttir (@katrintanja)

“We do a lot of tote bags, L-sit holders, ring holders, and hip extensions,” she said. “I do a lot of accessory moves around the big lifts.” Accessory movements are complementary exercises designed to support and improve performance in major movements, such as the squat or overhead press. Examples include Davidsdottir’s basic exercises, as well as many other exercises such as dumbbells, cranial breaks, and split squats.

A carry-on is a simple movement that involves holding a weight in one hand, engaging core muscles to keep the torso straight, and walking — and it can be done in everyday life like carrying groceries, Pilates instructor Natalie Hayward previously told Insider.

Davidsdottir wants her whole body to contribute to her every move

Davidsdottir said she does a lot of these accessory moves around her big lifts (like deadlifts, squats or clean and jerks) to make sure she can perform them safely and keep moving forward.

“I feel like I keep my body healthy a lot, and that helps with my big, sexy lifts,” she said.

In addition to strengthening her core, making sure her glutes are strong and engaged helps protect the back, says Davidsdottir.

“The important thing this year is to make my whole body contribute to everything I do,” she said.