changeofdirection

Change of direction (COD) refers to the ability to rapidly alter movement direction, typically involving a controlled deceleration followed by re-acceleration in a new vector. COD is a physical component of agility but can be studied independently to quantify how quickly an athlete can change direction, especially under maximal or near-maximal effort. It is commonly relevant in team and court sports, where players repeatedly need to redirect their momentum.

The COD process relies on braking forces, knee and hip alignment, and the ability to apply force in a new direction. Biomechanical factors include deceleration capacity, ground reaction forces, leg stiffness, and technique, such as the plant foot position, forefoot angle, and trunk control. Fatigue, surface and footwear, and neuromuscular coordination influence both performance and injury risk during rapid changes of direction.

Assessment in sport science frequently uses field tests such as the 505 test, Illinois agility test, T-test, and the 5-0-5 shuttle or pro-agility test (5-10-5). These tests measure time to complete directional changes and can be paired with linear sprint times to compute COD deficits, a metric that isolates the additional time required to change direction beyond straight-line speed.

Training to improve COD combines sprint work with plyometrics, eccentric strength, and braking drills, emphasizing technique such as controlled deceleration, proper plant foot placement, hip and knee alignment, and quick re-acceleration. Progressive loading, individualized programming, and surface-safety considerations are important to reduce injury risk, particularly to the knee and lower extremity joints. COD performance is context-specific, varying with speed, angle of change, and cognitive demands in reactive settings.