Dorsiflexion is a sagittal plane motion. The term is used to describe motion of the foot where the top (dorsal aspect) of the foot flexes toward the tibia. Dorsiflexion is generally thought of as occurring at the ankle, but there is also dorsiflexion that can occur at the mid-tarsal joint that separates the forefoot from the rearfoot. It is not restricted to the foot moving on a stationary tibia. Dorsiflexion also occurs when the tibia moves forward towards the foot, or when both the foot is moving towards the tibia and the tibia is moving forward to the foot.
There are times when the dorsiflexion should occur almost exclusively at the ankle, but there are other functional movements when the motion should occur in the ankle and the mid-foot. One of the “magical” biomechanical truths of the foot is that when the subtalar joint is pronated/everted, there will be motion available at the mid-tarsal joint. When the subtalar joint is supinated/inverted, the mid-foot motion should be very limited. Why is this important? Because when we land on the ground, we want the foot to be flexible so it can adapt to the surface while contributing to the loading of the muscles. However, when we want to propel off the ground to move forward during gait, a flexible foot would be a big mechanical disadvantage. This conversion of the mid-tarsal joint from mobile to stable (and back) created by subtalar joint position is critical to all types of function.
If we examine the most common human function, walking, the foot transforms from mobile to stable to in each walking cycle. Because the subtalar joint moves into a pronated position with heel strike and loading of the leg, the mid-tarsal joint mobility increases, facilitating shock absorption and surface adaptation. Dorsiflexion can occur at the ankle and mid-tarsal joints. Later in the cycle when the body moves over the foot prior to propulsion, the mid-tarsal joint becomes more stable and most of the ankle dorsiflexion at this time should occur at the ankle joint. Either a stable foot during loading or a mobile foot during propulsion will inhibit function and increase tissue stress.
When someone prepares to jump, dorsiflexion is essential. As the body drops down to load the muscles, the tibia moves forward creating ankle dorsiflexion. This loading also should move the subtalar joint into a pronated position, thereby making the mid-tarsal joint mobile. Gravity will drive the rearfoot down, which creates dorsiflexion at the mid-tarsal joint. Any restriction of these normal joint motions (preventing dorsiflexion for loading) will reduce the load. A poor load will inhibit the explode (jump).
Based on the two functional activities described above, it becomes evident that dorsiflexion must be available with the subtalar joint in both a pronated /everted and a supinated/inverted position. This biomechanical “truth” requires strategies to create three-dimensional flexibility movements during weight bearing. The body is driven over the foot in order to create dorsiflexion when the foot is mobile and when it is stable. This is accomplished by 1: positioning the subtalar joint in either position or 2: driving the body so that the subtalar joint motion (either pronation or supination) occurs simultaneously with the dorsiflexion.
Once the 3D flexibility is improved, functional movements are employed to make sure the body can “use” the new motion. Finally, programs must include movements that require loading into and exploding out of dorsiflexion to train the muscles to control the new motion.
The tweaking strategies learned in the Certification in Applied Functional Science (CAFS), as well as the Performance System of the 3D Movement Analysis and Performance System (3DMAPS) empower practitioners to create the proper environments and movements to create client success.