A strong core is crucial for nearly every physical movement. Many exercises exist for improving your midsection’s strength, stability, and definition. Most core exercises require minimal to no equipment and can be scaled according to experience or strength level.
The major muscle groups that the plank works include the core, glutes, hamstrings, upper back, and shoulder. Keep reading to discover why the plank is so effective for core strength.
Plank Muscles Worked
- Transverse Abdominis
- Rectus Abdominus
- Internal and External Obliques
- Erector Spinae
- Latissimus dorsi
- Quadratus Lumborum
The plank is one of the few core exercises that train the transverse abdominis, or TVA for short. Three flat muscles are found in the core’s anterolateral wall, of which the transverse abdominis is the deepest. The TVA is named after the direction its muscle fibers are arranged. It originates from the ribs all the way to the pelvis and wraps around the trunk from front to back.
The primary function of the TVA is spine and pelvis stabilization, trunk support, and internal organ protection. The TVA plays a key role in increasing intra-abdominal pressure, which is advantageous for bracing during various movements, such as deadlifts, squats, and overhead presses.
Without a strong and stable TVA, you cannot lift as much weight, so you’re performance will suffer, and injury risk may increase. A lot of people that have a weak TVA end up suffering from low back pain because the lumbar spine is unstable. Regarding aesthetics, activating your TVA is crucial for having a tight midsection and performing a vacuum pose for bodybuilding competitions.
The rectus abdominus, commonly called the “six-pack,” is the most superficial core muscle. Although other core movements are better suited for developing the rectus abdominus, it is active during the plank exercise.
The muscle group originates from the ribs to the pelvis and is located on the front of your midsection. Its primary function is to bring the rib cage closer to the pelvis, which is known as trunk flexion. Crunches, sit-ups, and leg raises all build and strengthen the rectus abdominus.
The rectus abdominus is important for overall core strength and stability, and is aesthetically the most pronounced.
Internal and External Obliques
Along with the TVA, the plank works the other two flat core muscles, which are the internal and external obliques. The internal oblique is located on the lateral sides of the abdomen. The internal oblique is named after the orientation of its muscle fibers and the fact that it lies underneath the external oblique.
Its muscle fibers are slanted and run superiormedially. Due to the direction of the muscle fibers, the internal obliques contribute to lateral flexion and rotation of the trunk to the same side. The internal obliques are also crucial for overall trunk stabilization.
The external obliques are located on each side of the abdomen as well, but they are located on top of the internal obliques. Its muscle fibers are also slanted, but they run inferiomedially. Due to the direction of the muscle fibers, the external obliques contribute to lateral flexion or rotation of the trunk to the opposite side. The external obliques are equally as important for strength and performance as they are for aesthetics.
Various sports and daily activities require rotation, so the obliques are very important core muscles. Perform the side plank for targeting the oblique muscles or improving balance.
The plank also works lower body muscles such as the glutes. The glutes, specifically the gluteus maximus, are one of the largest and strongest muscles in the body. The glutes, commonly called the butt, are important for nearly all human movement.
A total of three muscles – the gluteus maximus, gluteus medius, and gluteus minimus – each one performs a different action, but are all important for hip and pelvis movement and stabilization.
The gluteus maximus is responsible for hip extension, which allows us to stand upright. They work with the core musculature to stabilize the pelvis and lumbar spine. When performing the plank, contract the glutes to prevent the lower back from arching.
The plank works the hamstrings muscles, which are located on the back of your upper leg. Four muscles make up the hamstrings: biceps femoris long head, biceps femoris short head, semitendinosus, and semimembranosus. The two primary actions of the hamstrings are knee flexion and hip extension.
Since they work with the glutes to extend the hips, they are active during a plank to maintain proper form. Contracting the hamstrings and glutes will help keep the lower back from arching during the plank and places the core in a better position to stay engaged.
The hamstrings support movements such as squatting, deadlifting, walking, and running. They help stabilize the hip and knee joints, which is important for injury prevention. Hamstring exercises are ideal for overall balance in leg muscles.
The erector spinae, or spinal erectors, isometrically contract during the plank to keep a neutral spine. The erector spinae muscle group includes the spinalis, iliocostalis, and longissimus. The erector spinae are deep muscles that are located on each side of your spinal column and run from the base of your neck to your pelvis.
The erector spinae assists with spinal extension, lateral flexion, and stabilization. The erector spinae are most active during a hip-hinge movement, such as a deadlift or good morning. Nearly every movement performed in a day engages the erectors in some way.
Having strong erectors helps protects the spine from injury, especially to the lumbar spine (lower back). From an aesthetic standpoint, the erectors are noticeable on bodybuilding stages, especially near the lower back.
Planks work several upper body muscles, such as the latissimus dorsi. The latissimus dorsi, or “lats” for short, is a large superficial muscle that originates from the lower back and attaches to the humerus. Its main actions are shoulder extension, adduction, and internal rotation.
During a plank, your arms support your upper body to keep you in the plank position. The lats will be involved whether you’re performing a forearm plank, high plank, or side plank. Strong lats are beneficial because they are engaged in nearly every upper-body movement. Well-developed lats boost fitness performance on pressing movements because shoulders can press from a more stable position.
The lats are very important for physique athletes because they contribute to the required V-taper that gives the illusion of having a smaller waist.
Another back muscle that the plank works are the rhomboids. The rhomboids, including rhomboid major and rhomboid minor, are deep muscles that assist with scapular movement and stabilization. The rhomboids are located on each side of the shoulder blades.
The muscle’s primary actions are scapular retraction and rotation, for instance when performing any rowing movement, the rhomboids are activated. Working the rhomboids can help improve posture by pulling shoulders down and back.
Forward-rolled shoulders are common in people who have overdeveloped pectoral muscles and anterior deltoids. Strengthening the upper back muscles is one of the best ways to correct that.
Planks work the trapezius, known as the “traps,” a large, flat, superficial muscle that’s located on the upper back. Since the trap is such a large muscle, it’s divided into three areas based on how its muscle fibers are oriented – the upper, middle, and lower. The upper traps perform shoulder elevation, such as shrugging your shoulders.
The middle traps assist with retraction, so they are engaged heavily during rowing movements. The lower trap fibers perform shoulder depression. The main areas of the trap that are active during a plank are the upper and middle traps. The middle traps are especially important for maintaining the plank position. Strengthening your traps is beneficial for posture, shoulder health, and aesthetics.
The burning sensation in the shoulders when performing the plank occurs due to activation of the deltoids, also known as “delts,” including the anterior delt, lateral delt, and posterior delt. The delts are superficial muscles that act as primary movers.
The anterior or front delt performs shoulder flexion. The lateral or side delt performs shoulder adduction. The posterior or rear delt performs horizontal abduction. During a plank, they all work to stabilize your shoulder since your arms support your upper body.
A deeper group of muscles, known as the rotator cuff muscles, are also actively working to help stabilize your shoulder. The rotator cuff consists of the infraspinatus, supraspinatus, teres minor, and subscapularis. Most people that suffer from a shoulder injury end up tearing one or more of their rotator cuff muscles.
The plank works the quadratus lumborum. This muscle is often not talked about because it’s deep, so you don’t see it in the mirror. However, the quadratus lumborum (QL) is incredibly important for stabilizing your lumbar spine and pelvis. A tight or weak QL can lead to many problems, such as low back pain, postural issues, and instability.
The QL even plays a role in breathing by acting as an accessory inspiratory muscle. When your core is weak, the QL is more likely to become overworked from trying to compensate for that weakness. Overall, doing a plank can help keep everything aligned by strengthening your core.
Frequently Asked Questions
The plank can easily be modified to become more or less challenging. It can also be changed to target different muscles. While the forearm plank is considered to be the traditional plank exercise, there are also several variations. You may also be interested in the best plank alternatives.
Here are some great plank exercise variations you can try out:
– Forearm plank – standard plank exercise
– Knee plank – beginner
– Straight-arm plank – beginner
– Side plank – beginner to intermediate
– Reverse plank – intermediate
– Walking plank – advanced
– Shoulder-tap plank – advanced
– Spider-man plank – advanced
– Weighted plank – advanced
The main benefits of a plank exercise include:
– No equipment required
– Strengthens all core muscles
– Helps improve posture
– May reduce lower back injury
– Full-body exercise that trains multiple muscle groups simultaneously
– Improves stability and balance
– Can be scaled according to experience level
Spot-reducing is a common misconception in the fitness industry. Plank exercises will not reduce your belly fat, but theycan help tighten your midsection and build your abdominal muscles.