Why does my high jumper's lead leg stay bent going over the bar?
A free leg that never straightens usually costs height that a good plant already paid for, and it is a hard fault to see once the athlete is rotating.
The plant looks fine. The takeoff angle looks fine. And the athlete still clears the bar looking cramped, knee folded, almost sitting over it rather than extending through it. That gap between a good takeoff and a scrappy clearance usually comes down to one joint: the free, or lead, leg never straightens.
Why the kick matters
Driving the free leg straight at the top of the jump does two things: it helps carry the rotation that turns the athlete over the bar, and it lets that leg clear at close to its full length rather than folded up under the body, using less of the jump's total height to get it over. A bent free leg asks the jump to be higher than it needed to be, for a bar height that was already hard enough.
Usual causes
- A rushed penultimate step that leaves no time to drive the free knee up before takeoff.
- A learned flinch: an athlete who has clipped the bar with a shin before starts protecting that leg by keeping it tucked, whether or not the bar is actually close.
- Simple hip flexor strength or mobility, since driving a leg straight at speed against momentum takes real strength through the hip, not just flexibility on a table.
What the Film Room measures here
High jump reports hip rise as a share of body height, takeoff angle, and knee fold and extension, all read from the skeleton the app tracks frame by frame. Knee fold and extension is the one that speaks to this fault directly: it can show whether the leg is actually straightening at the top of the jump or staying folded the whole way over.
That reading is most reliable near takeoff, while the athlete is still roughly side-on to the camera. High jump is one of the few events in the Film Room where the athlete deliberately rotates through the shot, and once the hips and legs turn away from the lens, a 2D skeleton is estimating a joint angle that is no longer really in the plane it was measured in. Trust the number near the plant. Watch the peak of the jump with your own eyes.
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Related
Why your high jumper knocks the bar off on the way down
Legs taking the bar after the hips have cleared is a timing fault at the top, and usually a takeoff point that drifted before it.
Read →Why doesn't my high jumper's back arch over the bar?
A flat clearance over the bar usually starts well before the bar, in a plant and a shoulder position that never gave the arch anywhere to happen.
Read →Should the lead leg be straight over a hurdle?
Nearly, for an instant, but how the leg gets there matters far more than how straight it ends up.
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