What Muscles Does Running Build?
Running is a full body workout; one that engages nearly every major muscle group in the body. This revelation should come as no surprise for any runner who has ever woken up the morning following a hard workout or race, only to wonder why muscles in the arms, shoulders, or core are sore, in addition to legs. Here, the way muscles work when running will be discussed.
Running is simply the act of putting one foot in the front of the other, which makes the plantar fascia the most logical place to start in the functional discussion of running. While not technically a muscle (fascia is fibrous connective tissue), the plantar fascia sets running into motion. The plantar fascia supports the arch on the bottom of the foot and spans the distance from the heel bone to the metatarsals.
This piece of connective tissue tenses when weight is placed on the foot to support the arch, and carries 14% of the foot’s total load. When the foot is in contact with the ground, the plantar fascia lengthens 9 – 12% to prepare for the push off phase, and then acts as a spring for the conservation of energy. The plantar fascia also contributes to the “windlass mechanism”1, by tensing during dorsiflexion of the toes, then raising the arch, and finally by shortening the foot. This mechanism is important for efficient forward momentum.
Tibialis Posterior / Posterior Tibial Tendon
The posterior tibial tendon runs from the tibialis posterior muscle, which is found deep within the calf muscles, to the inside of the ankle, attaching to the medial malleoulus (the large bony bump fond on the inside of the ankle). The posterior tibial tendon is important for arch support and foot/ankle stabilization.
When a runner takes a step forward his or her toes dorsiflex, the plantar fascia tenses, and then his or her lower leg provides shock absorption upon impact.
The posterior tibial tendon stabilizes the foot by locking the ankle into place in order to maintain a rigid configuration for pushing off the ground. Additionally, the tendon works to keep a runner’s foot in a neutral position in order to avoid pronation (rolling to the inside of the foot) and supination (rolling to the outside of the foot).
Along the front of the shin bone is the tibialis anterior muscles. These muscles are important for supporting dorsiflexion within the toes. Proper degree of dorsiflexion2 is necessary to keep a runner’s feet from getting caught on the ground during forward momentum. For instance, if a runner did not flex his or her toes toward the sky, the toes would either drag the ground or the runner would swing his or her feet laterally in an inefficient motion in order to avoid tripping over objects.
Peroneals (not to be confused with perineal nerve) are comprised of the peroneus longus and peroneus brevis, which can be found spanning the outside of the shin into the lateral malleolus (outer ankle bone) and 5th metatarsal. For runners, the main function of the peroneals is to assist the calf muscles in plantarflexing the foot (i.e., pointing the foot downwards for push-off) as well as stabilizing the foot for a neutral ground strike.
There are three main muscles that comprise the calves: Gastrocnemeius, Soleus, and Plantaris. The Gastrocnemeius (sometimes called Gastroc for short) is primarily used to lift the runner’s heel from the ground as the athlete plantarflexes and springs forward. Similarly, the Soleus is used for plantarflexion, but only activates when the knee is bent.
Therefore, the Gastroc initiates plantarflexion before recruiting the Soleus. Finally, the Plantaris rotates the ankle joint and aids in stabilization. Additionally, the calf muscles work together to act as shock absorbers to protect the knee during the foot strike portion of a runner’s stride.
The Illiotibial Band – also called the IT Band for short – plays an important role in hip stabilization, as well as acting as a spring for releasing energy3. This long band of fascia, which runs from the top of the hip to below the knee, is engaged when the leg swings backward. The IT band stretches during the backswing in order to store the elastic energy. Then, when the leg swings forward the energy is released. In addition, the IT band is crucial for keeping knee and hip in the same plane while providing stabilization to the hips and preventing changes in alignment.
The hamstrings are one of the most significant muscles4 used for running, and include Biceps Femoris, Semitendinosus, and Semimebranosus. These muscles are engaged during the backswing motion, when the runner propels his or her leg backwards. They are also utilized to push the body forward by creating extension at the hip joint and flexion at the knee. Hamstring muscles are necessary for controlling inward rotation of the leg when the knee is flexed and they also help to stabilize the knee joint. Sprinters tend to have more well-defined hamstrings than distance runners, because the backswing motion and forward power is more exaggerated during sprinting.
The quadriceps muscle group comprises the four muscles that form the front of a runner’s thigh, between knee and hip. These muscles are the Vastus Medialis, Vastus Intermedius, Vastus Lateralis, and the Rectus Femoris. Quadriceps muscles are most important for driving the leg forward and for knee extension. For instance, the quads are engaged in conjunction with plantarflexion in order to lift the knee into the air and the flexed foot off the ground.
During the foot strike phase, the quads are utilized for straightening out the leg and acting as shock absorbers. Running for long periods of time downhill stresses the ability of the quadriceps muscles to absorb this strain while also stabilizing both the knees and hips, which is the primary job of the Rectus Femoris.
The hip flexors consist of Iliopsoas, Iliacus, and Psoas Major muscles and are located on the front of the hips. These muscles are active whenever the knee is driving upwards, such as during sprinting. Hip flexors are also necessary for hip stabilization. For those who live sedentary lifestyles5, the hip flexors are typically short and tight, resulting in a forward tilt of the pelvis. After plantarflexion and heel lift, the hip flexors work in conjunction with the quads and hamstrings to lift the knee and stabilize hips from extraneous movement.
The gluteal muscles are the ones which make up the posterior side of the hips, and are comprised of the Gluteus Medius, Gluteus Maximus, and Gluteus Minimus. The main purpose of the gluteal muscles is to assist in upright posture while also propelling the body forward. Specifically, the gluteus medius prevents the pelvis from dropping when a runner is balanced on one leg, and is also used for knee stabilization. Additionally, the gluteal muscles are responsible for decelerating leg swing as the foot makes contact with the ground.
Core strength is commonly overlooked by runners, because these muscles are not crucial for powering forward movement in the same way as gluteal or calf muscles. However, core muscles such as Transversus Abdominus (muscles that run on the outside of the “six pack” region), Obliques (muscles that run from outside of hips to ribcage), Erector Spinae (muscles that run vertically on either side of the spine), and Multifidus (deep muscles in the back) play an important role in a runner’s efficiency and speed.
The core muscles work together to stabilize joints and control a runner’s balance. These muscles are important for maintaining upright posture, while preventing lateral movements in the pelvis and spine. When arms and legs move in unison, the core comprises the connecting muscles to minimize extraneous movements that would otherwise hinder efficiency.
Core muscles also serve, to a small extent, as shock absorbers which are beneficial for creating a smooth ride and reducing the amount of impact experienced by the athlete.
Shoulders and Biceps
Finally, discussion about the muscles in the shoulders, as well as the biceps, will complete this guide on how muscles function when running. Arm motion is necessary for proper running form; however, until recently scientists assumed that arm strength propelled the lower body, with shoulders initiating the back and forth movement of the arms and biceps working to keep arms flexed while helping power arm swing.
Instead, researchers have proposed an alternative theory, which states that arms are actually passive mass dampers6 that are powered by the movements of a runner’s lower body. For this study, locomotor cost was measured while participants walked or ran on a treadmill under a variety of arm swing conditions. Changing the moment of inertia in the upper body affected phase difference between shoulder and hip rotation, suggesting arms were mass dampers.
Surprisingly, the restriction of arm swing did not affect locomotor cost, which further supports the mass damp theory. Therefore, the main purpose of the shoulder and bicep muscles during running is to reduce torso and head rotation, not to power leg movement.
1. Bolgla, L. A., & Malone, T. R. (2004). Plantar Fasciitis and the Windlass Mechanism: A Biomechanical Link to Clinical Practice. Journal of Athletic Training, 39(1), 77–82. Link
2. Fong, C.-M., Blackburn, J. T., Norcross, M. F., McGrath, M., & Padua, D. A. (2011). Ankle-Dorsiflexion Range of Motion and Landing Biomechanics. Journal of Athletic Training, 46(1), 5–10. http://doi.org/10.4085/1062-6050-46.1.5 Link
3. Eng CM, Arnold AS, The human iliotibial band is specialized for elastic energy storage compared with the chimp fascia lata, J Exp Biol. 2015 Aug;218(Pt 15):2382-93. doi: 10.1242/jeb.117952. Epub 2015 May 29. Link
4. Chumanov, E. S., Heiderscheit, B. C., & Thelen, D. G. (2011). Hamstring Musculotendon Dynamics during Stance and Swing Phases of High Speed Running. Medicine and Science in Sports and Exercise, 43(3), 525–532. http://doi.org/10.1249/MSS.0b013e3181f23fe8 Link
5. Riley P.O., Franz J., Dicharry J., Kerrigan D.C., Changes in hip joint muscle-tendon lengths with mode of locomotion. Gait Posture. 2010 Feb;31(2):279-83. doi: 10.1016/j.gaitpost.2009.11.005. Link
6. Pontzer H1, Holloway JH, Control and function of arm swing in human walking and running. J Exp Biol. 2009 Feb;212(Pt 4):523-34. doi: 10.1242/jeb.024927. Link