Jen Rulon

Let us begin by fixing a widespread misconception. Your core is not limited to your abdominal muscles. Your glutes, back, obliques, and many other muscles are a part of your core. Together, they represent the most important group of muscles in your body.

Why is my Core so Important?

You have likely been advised to do core work before. But has anyone told you why? First, consider how your body moves through swimming, biking, and running. Then, when we add what the core is responsible for, the reason why so many experts tell you to do the core will become evident.

Reason 1: Injury Prevention

You’ve likely heard this as well, but it is tough to understand how this works. As the center of your body, your core is responsible for holding everything else in line to facilitate proper biomechanics. If your core fails, your form starts to break down, and other muscles and ligaments are kicked into overdrive to pick up the slack, leading to injury.

Reason 2: Efficiency

For similar reasons, the core helps prevent injuries and keeps you efficient. Especially in swimming and running, your body is doing a lot of twisting side to side, and we call that transverse movement. While some transverse movement is necessary to swim and run, the fastest point from point a to point b is always straight. Furthermore, whenever your body spends energy moving to the side, it has to spend more energy stopping that movement and pulling it back to the other side. So, again, the core is what is primarily responsible for this. And don’t get me wrong; your core will make holding that uncomfortable time trial position on the bike more accessible.

Here is a visual for you. Take something lengthy and straight, like a toothpick. Put your finger on one of the ends and let it rotate. Now do the same thing with your finger in the middle. When you are in the center of the toothpick, it takes much less energy to rotate the toothpick. Also, if you try to twist the toothpick from the outside with one hand while holding it in place with the other hand in the middle, the hand in the middle will always win. Your core is that hand in the middle. You want your core to hold your body in line because the further you go, the more energy it takes.

Reason 3: Balance and Stability

This feeds into both reasons one and two. Swimming moves forward as smoothly as possible, aided by keeping your trunk stable in the water. Running is a constant process of balancing on one foot before transferring to the other. Cycling, well, the importance of balance on a bike should be obvious. If you lose it, you eat asphalt. But even more so, improved balance and stability will help you hold a straight line easier and allow you to corner better. In each of these situations, your core is primarily responsible; without it, you risk both injury and inefficiency.

Doesn’t Swimming, Cycling, and Running already work my core?

It does, but what it does is core activation. Of course, it would be best to have more than that to build strong muscles. That is why all top triathletes do specific core workouts at least three times a week, with many doing it daily. The core is the foundation on which you build your swimming, cycling, and running fitness. It keeps you healthy, makes you strong, and allows you to maximize your aerobic capacity by increasing your efficiency. 

We encourage you to work core into your routine 3-4 times weekly. Don’t just do crunches, either. Instead, incorporate movements like glute bridge raises, dead bugs, supermans, planks, windshield wipers, Russian twists, and flutter kicks to work your core in many different ways. Below are some examples of core work I do that you may want to incorporate into your routine.

Glute Bridge Raises

It is a simple, repetitive movement that is very easy to perform. It works the entire lower body, mid-section, and core:

Lay down on the floor on your back with palms facing upwards.

Pull in your heels, so they are close to your bum.

Lift your hips as high as you can into the air.

Push up with your hips; don’t arch your back.

Engage your core muscles to help with the move.

Hold the position with your bum raised for a moment.

Drop your bum down and let it touch the floor lightly.

Repeat the move.

You can aim for 3 -4 rounds of 15 to 20 repetitions.


Dead-bug works the entire body and is excellent for coordination.

Lay down with your back on the floor.

Put all four limbs in the air.

Keep your lower back on the floor.

Lower your right arm alongside your head until your hand touches the ground.

Your bicep should be beside your ear.

At the same time, lower your left leg to the floor so that it is parallel to the ground.

Hold the position momentarily, and then bring your right arm and left leg back to the original position so that all four limbs are back in the air.

Alternate sides.

Do as many repetitions as possible.


Plank works all the bones and joints in the body and is excellent for strength, coordination, and balance.

Get down on your hands and knees.

Then scoot your arms and body forward and lower yourself, so your weight rests on your elbows and forearms.

Your elbows should be directly below your shoulders.

Your knees should still be on the ground.

Hold this position for as long as possible, and aim for 30 seconds.

Once you have mastered this, try a more difficult move:

Keep your upper body in the same position with your elbows on the floor.

Get your knees off the floor; your weight will rest on your toes.

Keep your body straight like a plank of wood.

Do not let your back or hips sag.

Hold the position for as long as possible.

Hanging Knee Raises (Knees to Elbows or Toes to Bar are the CrossFit Version)

You will need a bar to hang from.

Grab the bar width to your liking.

While keeping your arms and back straight and legs straight without touching the floor.

Start pulling your knees up by using your core and lifting them as high as possible. You can hit your core or your high flexors. Depending on how much you swing. 

Lower the knees back down and try to limit the swinging. 

Are you interested in learning more about strength training for the endurance athlete or the everyday human? Well, you are in luck! I have my OWN app coming out and I am “oh so excited!”

Click HERE to learn more today! 


AUTHOR: Jen Rulon

I have been coaching triathletes, runners, and cyclists for over 21+ years; I received my Master's Degree in Kinesiology with an emphasis in Exercise Science. And as you may have learned, there is more to life than swimming, biking, and running. It is a lifestyle, and I am here to help you cross that finish line with a smile, whether it is an Ironman Triathlon or the Ironman of Life. You can find my knowledge shared in Triathlete Magazine, Runners World, on the TEDx Stage, the Health and Wellness Expo in San Antonio, TX, Southwest Research Institute Human Performance Summit, Training Peaks Workshops, "Self Motivation Strategies for Women" on Amazon, Men's Journal Online, and the New York Times. I also practice what I preach—she's a 15x Ironman Triathlete who participated in the Ironman World Championship in Kona, Hawaii, on October 14, 2017.

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