The movement often described as the hand or foot “rolling outward” is a biomechanical event known primarily as supination, or sometimes underpronation. This motion involves the weight of the body concentrating along the lateral, or outer, edge of the foot during walking or running. While the term applies to both the hand and the foot, the outward rolling in the foot, affecting gait and lower body alignment, is the far more common concern.
Understanding Supination in Foot Mechanics
Supination is a natural component of the foot’s movement cycle, necessary for providing a rigid lever to push off the ground. In a balanced stride, the foot first rolls slightly inward (pronation) to absorb the shock of heel strike and adapt to the ground surface. Following this shock absorption phase, the foot transitions to supination just before the “toe-off” phase, stabilizing the foot to propel the body forward. Excessive supination, however, means the foot does not pronate enough to effectively absorb impact forces.
When the foot remains excessively supinated, the weight transfer is concentrated entirely on the outer edge. This prevents the foot from using its natural arch flexibility to cushion the impact, essentially turning it into a rigid structure. The lack of inward roll means that the ground reaction forces are transmitted up the leg, placing increased strain on the ankle, Achilles tendon, and lateral lower leg muscles. This abnormal pattern is often identified by a shoe wear pattern that is significantly heavier on the outside heel and outer ball of the foot.
The foot is less able to adapt to uneven terrain, which can lead to instability and a higher risk of ankle sprains. Ankle injuries and pain in the heel, arch, or shin are common complaints that stem from this prolonged, uneven distribution of force.
Underlying Causes of Excessive Outward Rolling
The tendency toward excessive supination is frequently related to inherited structural characteristics of the foot and leg. People with naturally high arches, a condition known as pes cavus, often have a rigid foot structure that resists the necessary inward roll for shock absorption. This innate rigidity makes it difficult for the foot to flatten and absorb impact during the stance phase of gait.
Muscle imbalances or weakness in the lower leg can also contribute to the outward roll. Weakness in the peroneal muscles, which control the inward motion of the foot, can allow the foot to drift into supination. Similarly, tightness in the Achilles tendon or calf muscles can restrict the ankle’s range of motion, forcing the foot to compensate by rolling outward.
Other factors that influence a supinated gait include past injuries, such as a previous ankle sprain, which can lead to instability and subsequent compensation. A difference in leg lengths can also cause one foot to supinate more than the other as the body attempts to balance the pelvis. Furthermore, choosing footwear that is rigid, lacks cushioning, or is worn out can exacerbate a pre-existing tendency toward supination.
Corrective Measures and Management
Managing excessive supination focuses on promoting better shock absorption and encouraging a more neutral foot alignment during movement. A foundational step involves selecting appropriate footwear that provides extra cushioning, especially in the midsole, to absorb impact forces that the foot structure cannot. Shoes should also be lightweight with a roomy toe box.
Orthotic devices are often recommended to redistribute pressure and gently guide the foot toward a more balanced position. While over-the-counter insoles can offer some arch and heel support, custom-made orthotics are designed specifically for the individual’s foot contour to control the motion and reduce pressure on the outer foot. These inserts help to provide the support and cushioning that a rigid, high-arched foot lacks.
Physical therapy and specific exercises are important for addressing muscle weakness and tightness. Stretching the calf and Achilles tendon can improve ankle flexibility, which is often restricted in supinated feet. Strengthening exercises that target the tibialis anterior muscle can also help to balance the forces acting on the foot and enhance overall stability. Consulting with a podiatrist or physical therapist can lead to a gait analysis that identifies the specific biomechanical issues and dictates the most effective treatment plan.
Addressing Outward Rolling in the Hand
The outward rolling motion in the hand is typically a separate phenomenon from foot supination, involving the rotation of the forearm and wrist. Supination in the forearm refers to turning the palm upward or forward, which is a normal, controlled movement. However, an involuntary or sustained outward position of the hand suggests a neurological issue rather than a structural gait problem.
One potential cause is a movement disorder like focal dystonia, which involves involuntary muscle spasms and abnormal posturing. This condition can affect the hand and wrist, causing the hand to twist into an unnatural position. Focal hand dystonia is often task-specific, meaning it appears during fine motor activities like writing or playing a musical instrument.
Other neurological conditions, such as those related to nerve damage, stroke, or Parkinson’s disease, can also manifest as uncontrolled or rigid hand postures. If a person experiences involuntary outward rolling or twisting of the hand, a medical evaluation is necessary. A specialist can determine the underlying cause and recommend appropriate treatment, which may involve medication or specialized physical therapy.