Does the Side Plank Exercise Strengthen the Back?

Smiling man doing a side plank in a gray shirt and blue shorts.

The side plank, or side bridge, is a core exercise that challenges the muscles on the sides of your body to hold you body in place. Much like the regular front plank, the side plank requires concentration to stay as stiff as possible. It is more of an endurance exercise than a strength exercise but the endurance that it builds in your abdominal and lower back muscles can help protect your spine.

It's a unique exercise because it targets muscles on the sides on the core whereas most core exercises focus on either the front or the back. These include the obliques and gluteus medius. While the back muscles are involved, they don't play as big of a role as other core and hip muscles.

How To Do the Side Plank

To do a side plank, start by lying on the ground on your side. Your forearm should be planted on the floor with your elbow on the ground right under your shoulder. Form a straight line from your head to your ankles with your feet and legs stacked on top of each other. From this position, simply raise your hips up and hold them in the air as long as possible.

Variations of the Side Plank

Explore other variations of the side plank to further challenge your core. The side bridge, which spine biomechanics researcher Stuart McGill made famous, is performed with your knees bent at 90 degrees and resting on the ground, making it slightly less challenging. You can also raise your top leg in a normal side plank to put more stress on your hip and core muscles.

The side plank is considered an endurance activity for the core by Dr. McGill, according to an he wrote article that was published by the National Strength and Conditioning Association. He believes that it's important for spine health for the muscles surrounding the spine, the core muscles, to be able to stay strong for an extended period of time. However, just because this exercise helps protect your spine does not necessarily mean that it works the muscles of the back.

What is Considered Strengthening?

Technically, in order to be considered a strengthening exercise, a muscle has to be stimulated to over 50 percent of its maximum potential. This is measured by something called electromyography (EMG), which involves researchers placing electrodes on a subject's skin to measure the amount of effort the muscles use during exercise.

External Oblique

According to one such EMG study, the external abdominal oblique is one of the most used muscles during the side plank. This ab muscle runs along the side of your body. This study, published in 2014 in Sports Health, tested muscle activity in different variations of the side plank.

The researchers found that in three out of the four different variations of the side plank tested, the obliques had more muscle activity than the back muscles. While the obliques were the most recruited muscle, they only crossed the 50 percent threshold in one of the variations to classify it as a strengthening exercise. This means that for all core muscles the side plank will be an endurance activity for most people.

Man is doing side plank pose

Side planks are an endurance exercise for your core.

Another study, published in the Journal of Orthopedic and Sports Physical Therapy in 2010, showed that the external obliques are activated almost five times more than the erector spinae, a lower back muscle, during the side plank, especially when performed on an unstable surface.

Back Muscles

The back muscles that are used in the side plank are: the erector spinae, multifidus and longissimus thoracis. These muscles act to stabilize your spine, preventing it from bending to the side, and also extend your lower back. A study on Georgia Regents University's website compared the core and hip muscle activation during front planks, side planks, bridges, and lunges. The results of the study show that the side plank recruited the lower back muscles more than lunges, back bridges or front planks. They also found that females recruited their back muscles more than males while holding the side plank position.

Hip Muscles

Even though the side plank uses the back muscles to help you stay in position, it doesn't use those muscles as much as others. The hip muscles are a great example. The gluteus medius, found on the side of your hip, was shown to be recruited at 100 percent of its maximal effort in a paper published in the Strength and Conditioning Journal in 2013. This is more than double the amount of activation shown in the back muscles.