How to Strengthen Inner Thighs Using Copenhagen Planks for Better Running and Stability

If you’ve ever experienced soreness in your inner thighs after a run or workout, you’re not alone. Many runners and athletes unknowingly neglect the muscles responsible for stabilizing the legs during every stride—your adductors, or inner thigh muscles. So, if you’re wondering how to strengthen inner thighs, you’re in the right place. In this article, we’ll explore why adductor strength is essential for injury prevention and better running performance, introducing the versatile Copenhagen plank as a must-have exercise. With detailed progressions to meet your body where you are, you’ll learn how to build strength and enhance your stride. Whether you're new to these exercises or looking to progress, these tips will guide you on the path to stronger inner thighs and improved athletic performance.

Why Adductor Strength Is Important

It never fails that whenever one of my non-runner colleagues, who regularly strength train, go for a first time run, they come back and say “wow, I’m more sore than I expected.”

I say, “let me guess: adductors.”

And I’m always right!

Are you skipping over your Adductors in your training? Don’t! They are working throughout your entire stride!

Adductor strength plays a key role in running, contributing to both stability and efficiency with every step. The adductors, your inner thigh muscles, help control lateral movement of the leg and stabilize the pelvis. They are worked throughout all of the stance phase of running to do so. When these muscles are strong, they create a solid foundation for the hips to move efficiently, reducing unnecessary side-to-side pelvis tilting, supporting rotation and improving overall running economy.

Learning how to strengthen inner thighs by incorporating adductor-focused exercises into your strength training routine not only supports injury prevention but also enhances your ability to maintain proper alignment and power during both long runs and speedwork. 

Adductors are often neglected in direct strength training but are an essential part of the muscles you use in your stride. They are quietly working to keep you moving smoothly and efficiently with every single step. 

How to Strengthen Inner Thighs: The Copenhagen Plank

The Copenhagen plank uses the inner thigh of the top leg and your core to support your body weight and stabilize your hips and pelvis, mimicking the demands placed on the adductors during running. Unlike isolated adductor strengthening exercises, the Copenhagen plank trains the adductors in a way that integrates your internal obliques, another super important muscle in stance phase that works together with that adductors for strong and efficient stride.

The Copenhagen plank is also super versatile. It can be easily modified to meet your body where it is and progress from there, making it a go-to exercise for everyone to use for building adductor strength, improving pelvic stability, and enhancing overall running performance.

You better believe these progressions are included in Strong & Stable: The Ultimate Hip Strengthening Program for Female Runners!

Try These Copenhagen Progressions

The Copenhagen plank can be a very humbling exercise, while also being one of the best when it comes to how to strengthen inner thighs. It’s important to meet yourself where you are with these and then slowly build over time. It took me MONTHS to go from the first one to the last!

In all of the exercises you will have the top leg elevated on a surface like a bench or chair. You will be pushing down into that surface with your inner leg, so you may want to add a cushion if the surface is hard.

Active Copenhagen Plank with Bottom Leg Support

In this first progression, you will keep the bottom leg on the ground for support. I do not look at this as cheating, but more of a two-for-one exercise. You will be getting adductors on the top leg and glute med on the bottom leg at the same time. For the sake of progressing to the other variations, slowly work on unweighting the lower leg over time.

90-90 Copenhagen Plank Hold

When you are ready, lift that bottom leg fully off the ground, bent up to 90 degrees of hip flexion. Progress to being about to hold this for 30 seconds over time.

Copenhagen with Adductor Lifts

This variation works the adductors of both legs at the same time! You can try this with the lower leg straight or bent. Holding the Copenhagen plank, lift and lower that bottom leg.

Copenhagen Crunch

When you are ready you can add in a cross body crunch for a bit more oblique engagement.

DNS Copenhagen

DNS stands for Dynamic Neuromuscular Stabilization. This variation has you rotating over that “stance leg” just like in your running stride.

Then, go through all the progressions again with the top leg straight out with only the lower leg/ankle/foot on the bench.

Now that you know how to strengthen inner thighs, remember to meet yourself where you are and you’ll progress over time from there. Don’t rush the process!

Next on Your Reading List:

Running: Hip Drop Exercise That Actually Works

Run Like a Queen: 5 Pelvic Floor Exercises For Women

Muscle Imbalance in Your Legs: Symptoms of an Inefficient Running Stride