Why does my high jumper's free leg not pull them over the bar?
The free leg is supposed to do work at takeoff, and when it just comes along for the ride the jumper is clearing the bar on the plant leg alone.
In a flop takeoff, one leg plants and one leg is free to drive. A jumper whose free leg stays passive, trailing rather than driving, is asking the plant leg to do a job built for two legs, and the bar usually knows it before the coach does.
What the free leg should be doing
The free knee should drive up hard at takeoff, the same action as the knee drive out of the blocks or over a hurdle, just aimed vertically instead of forward. That drive adds lift and starts the rotation that gets the jumper's back to the bar. A free leg that does not do this leaves all the lifting to the plant leg's extension, which has a ceiling.
- The free leg trails low and nearly straight instead of folding and driving up.
- It kicks out to the side rather than driving straight up, which steals rotation instead of adding it.
- It crosses over the plant leg during takeoff, which is awkward to fix because it usually started as a cue meant to help.
- It stops moving the instant the plant foot lands, as if the job ended at ground contact rather than continuing through it.
What to check on film
The Film Room's high jump setting reads hip rise as a share of body height, takeoff angle, and knee fold and extension. That last measure does not separate the free leg from the plant leg automatically, so when a jumper's hip rise is lower than their takeoff angle would predict, watch which knee the fold is actually describing before deciding which leg to coach.
What a single 2D camera cannot tell you: a free leg that kicks out sideways instead of driving straight up, because sideways motion at the bar runs toward and away from a side-on lens rather than across it. That fault reads on film as the leg simply not moving much, which is the wrong diagnosis. A back-on angle catches it; the side-on one cannot.
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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.
Read →Why does my high jumper's takeoff leg stay bent instead of straightening at the top of the jump?
The takeoff leg is meant to snap straight in a fraction of a second, and whatever extension goes missing there, height goes missing with it.
Read →Why does your high jumper rotate too early over the bar?
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