Why does my high jumper keep slipping on the curve of the approach?
A curve run upright puts sideways load on the foot that the surface cannot always grip, and the slip usually happens before anyone is looking at the plant.
A high jumper sliding on the curved part of a J-approach almost always gets the blame put on the plant foot, because that is the step everybody is watching. More often the problem started two or three strides earlier, on the bend itself.
Lean versus grip
Running a curve properly means leaning into it the way a cyclist leans into a banked turn, so the body's weight points through the foot rather than out to one side. A jumper who stays upright through the curve is asking each footstrike to resist sideways force with friction alone, and friction has a limit. Past that limit, the foot does not grip, it skids.
- Running the curve upright instead of leaning into it, which is the single most common cause.
- Spikes with the wrong pin length or pattern for the runway surface, or pins worn down from overuse.
- A wet, dusty or recently resurfaced runway, which changes the grip available on any given day.
- Trying to run the curve faster than the current amount of lean can actually support.
What to check first
Film the full approach from behind rather than just the plant, and watch the trunk angle through the curve itself. An athlete who looks fine at takeoff but unstable two strides earlier on the bend is dealing with a lean problem, not a plant problem, and fixing the plant will not touch it.
A single 2D camera filming the takeoff reads hip rise, takeoff angle and knee fold and extension at the plant. It has nothing to say about a foot sliding on the curve a few strides before that, and nothing at all to say about surface grip or spike wear, which are questions about friction that no camera angle can measure.
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Related
Should a high jumper run a J-curve or a straight approach?
The curve does part of the takeoff's job before the athlete ever leaves the ground, and a straight approach is easier to teach a beginner who has not earned that yet.
Read →Why does your high jumper's plant foot never land in the same spot?
A side-on camera reads the vertical arc of a jump well and has no idea where the plant foot actually landed on the ground, which is usually the real question.
Read →Why does my high jumper's plant foot point away from the bar?
A plant foot that turns away from the bar instead of pointing down the runway usually still clears, which is exactly why it goes unnoticed for seasons.
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