The tibialis posterior muscle is located deep in the lower leg and is often overlooked until dysfunction causes pain or mechanical issues. This muscle acts as a primary stabilizer, maintaining the structure of the foot and ankle during movement. Strengthening this muscle is an important step toward preventing common foot and lower leg problems. This guide offers a progressive approach to building strength in this stabilizing muscle.
The Role of the Tibialis Posterior
The tibialis posterior is located deep in the lower leg, nestled between the tibia and the fibula. Its tendon wraps behind the inner ankle bone and attaches to multiple bones on the underside of the foot, including the navicular and cuneiforms. Its primary mechanical actions are inversion and plantarflexion of the foot.
During weight-bearing activities like walking or running, the muscle maintains the integrity of the medial longitudinal arch. As the foot rolls inward (pronation) to absorb shock, the tibialis posterior contracts eccentrically to control this movement and prevent excessive arch collapse. A strong tibialis posterior supports the foot’s arch against body weight, ensuring proper foot mechanics.
Foundational Strengthening Exercises
Initial strengthening should focus on isolated, non-weight-bearing movements. The Seated Band Inversion exercise targets the muscle’s mechanical action without the complexity of balancing body weight. Sit with the leg to be exercised crossed over the opposite knee, with a resistance band looped around the forefoot.
The opposing end of the band should be anchored under the non-working foot or a stable object, pulling the working foot slightly outward (into eversion). Slowly pull the foot inward and slightly downward against the band’s resistance (inversion and plantarflexion). Execute the movement slowly, especially the return phase, controlling the band as it pulls the foot back to the starting position. Aim for 3 sets of 10 to 15 repetitions, ensuring the movement originates only from the ankle.
The Foot Arch “Doming” exercise directly engages the tibialis posterior and the deep intrinsic foot muscles. Sit with the foot flat on the floor, then try to shorten the foot by pulling the base of the big toe back toward the heel without curling the toes. This action should lift the arch slightly, creating a dome shape, while the heel and toe mounds remain on the ground. Hold the contraction for 5 to 10 seconds before relaxing, repeating this subtle movement for 10 to 15 repetitions. Mastering this exercise improves the motor control needed to support the arch during weight-bearing activities.
Advanced Functional Progression
Once isolated strength is established, the next phase involves transitioning to functional, weight-bearing exercises. The Eccentric Heel Raise is a primary progression that integrates the tibialis posterior with the calf muscles while emphasizing control. Begin by standing on a step with the balls of both feet and perform a standard double-leg calf raise.
At the top of the movement, shift weight onto the working foot, and then slowly lower the heel back down over a count of three to five seconds. This controlled lowering phase, known as the eccentric contraction, is effective for building tendon resilience and strength. Aim for three sets of 10 to 12 repetitions on each leg, focusing on keeping the heel bone tracking straight up and down without the foot rolling outward.
Progressing to Single-Leg Balance challenges the tibialis posterior to stabilize the arch dynamically while controlling body weight. Start by standing on one leg on a stable surface for 30 to 60 seconds. As this becomes easier, introduce instability by standing on a folded towel or a foam pad, which forces the muscle to maintain balance. Further progression involves incorporating controlled movement, such as reaching the opposite foot in various directions or performing a single-leg Romanian Deadlift (RDL). These movements increase the demand on the tibialis posterior to maintain a stable arch under dynamic loads.
Recognizing Weakness and When to Seek Help
Weakness or dysfunction in the tibialis posterior often causes pain or swelling along the inner ankle or arch of the foot. A common sign is a noticeable flattening of the arch, sometimes referred to as adult-acquired flatfoot, which results from the muscle failing to maintain arch height. Other indicators include tenderness when pressing along the tendon’s path and difficulty performing a single-leg heel raise. Inability to rise onto the toes, or an outward rolling of the ankle during this action, signals muscle insufficiency.
Seek consultation from a physical therapist or podiatrist if the pain is severe, if there is a rapid or pronounced collapse of the foot’s arch, or if you are unable to bear weight without significant discomfort. Professional help is also warranted if the arch collapse becomes rigid, meaning the arch does not reappear when the foot is non-weight-bearing. These symptoms can indicate a more advanced stage of tendon dysfunction that requires specialized medical intervention to prevent further deterioration of the foot structure.