Vertical oscillation is the vertical rise and fall of the body during running, usually expressed as the distance between the lowest and highest point of the center of mass, or a proxy for it, within each step. The body is lowest around mid-stance and highest during the flight phase.
Some running watches and sensors also report a vertical ratio, which compares vertical oscillation with step length. This helps account for the fact that faster, longer steps usually involve some vertical movement.
Why It Is Observed
- Large vertical movement may reflect extra effort directed upward rather than forward
- Very little vertical movement can accompany short, shuffling steps
- Changes in cadence, step length, and speed affect it
- It can be compared before and after technique changes or between fatigued and fresh running
There is no single ideal value. Runners differ in body size, speed, and style, and moderate oscillation is a normal part of running.
Measuring It on Video
- Use a side view, with the camera perpendicular to the running direction and level
- Track a landmark near the center of mass, such as a point on the pelvis or the waistband, rather than the head
- Calibrate the image using a known vertical distance in the same plane as the runner
- Compare the lowest point near mid-stance with the highest point during flight
- Treadmill video makes it easier to keep the runner at a constant distance from the camera
Common Pitfalls
- Head movement does not always match center-of-mass movement
- Clothing and waistbands can shift independently of the pelvis
- Overground runners moving across the frame change distance and viewing angle, adding perspective error
- Without calibration, video shows relative change rather than true centimeters
- Sensor readings and video estimates may not match exactly because they use different methods
Frame-by-frame review with a horizontal reference line drawn at the runner's lowest point can make vertical movement easy to see even when exact distances are not needed.