armswinging

Armswinging refers to the coordinated motion of the arms during locomotion in humans and other bipeds, typically opposite to the movement of the legs. It is normally an automatic aspect of walking and running, helping stabilize the body and maintain balance. In some conditions or contexts, arm swing may be reduced or exaggerated.

The mechanics of armswinging involve primarily the shoulder joints with elbow flexion and extension creating a pendulum-like motion. The arms swing in the sagittal plane, while the trunk and pelvis rotate in the opposite direction to the arms, producing a counter-rotation that helps balance angular momentum and stabilize the torso during stepping.

Functionally, arm swing contributes to gait efficiency and stability. It supports balance by counteracting upper-body rotation and can reduce energy costs associated with locomotion when coordinated with leg movement. Restricting arm swing has been shown to increase energy expenditure, and arm swing patterns can subtly influence propulsion dynamics during faster movements such as running or sprinting.

Variations in arm swing occur with speed, fatigue, age, and athletic training. Amplitude and timing typically increase with faster walking or running. Pathologies affecting the nervous system, joints, or muscles can produce asymmetries or diminished arm swing, which may be targeted in rehabilitation to improve overall gait.

In evolutionary and comparative contexts, modern human arm swing is associated with efficient bipedal locomotion, while other primates and extinct hominins exhibit different limb coordination and locomotor strategies, reflecting diverse adaptations in upper- and lower-body movement.