Triple extension is the combined extension of the hip and knee with plantarflexion of the ankle. It describes the position and action of the lower body when it drives forcefully against the ground, as in jumping, sprint starts and acceleration, Olympic weightlifting, and many explosive sport movements.
Although the term suggests three joints straightening at once, the joints usually extend in a coordinated sequence. In many jumps, the hip begins extending before the knee and ankle, with ankle plantarflexion contributing late in the push. The term is best understood as a coaching description of a powerful lower-body push rather than as a precise timing rule.
Where It Appears
- Vertical jumps and broad jumps at takeoff
- Sprint starts and the acceleration phase
- The second pull of the clean and snatch
- Volleyball and basketball takeoffs
- Push-off in skating and some swimming starts
Filming and Observing It
- Use a side view, with the camera perpendicular to the sagittal plane at roughly hip height
- Keep the whole body, including the feet, in frame
- Use 120 fps or higher to see the sequence of hip, knee, and ankle extension
- Draw angles at the hip, knee, and ankle at the frame of takeoff or full extension
- Compare the timing of each joint's extension across frames
Common Pitfalls
- Full extension of every joint is not always the goal; in sprinting, the knee is commonly not fully straight at toe-off
- Focusing on the end position can hide what happens earlier in the push
- Loose clothing and shoes can hide ankle and hip landmarks
- A camera that is not perpendicular to the movement distorts joint angles
Frame-by-frame review with angle measurements at the hip, knee, and ankle can help show how and when an athlete reaches extension, and whether it changes with fatigue or training.