The phases of the running stride
The running gait cycle describes one complete stride for a single leg, from initial ground contact to the next contact of the same foot. It divides broadly into stance (when the foot is on the ground) and swing (when it is in the air). Unlike walking, running includes a flight phase in which neither foot touches the ground, which is the defining mechanical difference between the two.
Within stance, the foot moves through initial contact, midstance where the body passes over the planted foot, and propulsion as the foot pushes off. Swing carries the leg forward to prepare for the next contact.
Where running injuries tend to arise
The stance phase is where the body absorbs ground reaction forces of several times body weight, so it is closely studied in relation to injury. Loading patterns at initial contact and during midstance are linked to stresses at the foot, shin, knee, and hip.
Many common running injuries are overuse conditions tied to cumulative loading, training errors, and mechanics rather than a single event. Gradual progression in volume and intensity is the most consistently supported way to reduce risk, and persistent pain warrants assessment by a qualified clinician.