Why does my runner bounce up and down instead of covering ground?
Extra vertical bounce is effort spent fighting gravity instead of moving forward, and it is most costly in the distance runners who can least afford to waste it.
Watch a runner from the side for long enough and some athletes seem to travel mostly up and down, with the forward progress almost an afterthought. Coaches usually call it bouncing, and it is worth separating from the faults that look similar, because the fix is not the same one.
Where the bounce comes from
- Reaching the foot out in front of the hips to lengthen the stride, which brakes on landing and sends the leftover energy up rather than forward.
- Weak hip and glute extension, so the push off the ground pops the body upward because there is not enough strength to drive it back.
- A cue like 'run tall' taken too literally, which some athletes turn into a vertical lift rather than a level trunk.
Why it costs more over distance
A sprinter's race is over in seconds, so a few centimetres of unnecessary lift barely registers before the line. A distance runner repeats that same wasted lift thousands of times, and energy spent going up is energy not spent going forward. This is one of the more common, least visible reasons two runners with similar strength and similar times in short reps separate badly over a longer distance: one of them is paying a small tax on every single stride.
Where the Film Room helps and where it does not
The sprint setting reports ground contact time and flight time. A long flight time next to a normal ground contact time and a normal cadence is a hint that the athlete is spending that airtime going up rather than forward, and worth a second look. What it will not do is hand you a number in centimetres for how much the body actually rises and falls. That measurement needs a fixed vertical reference in frame and the kind of frame-by-frame tracking built for calibrated distance, which is not what a single running clip gives you.
So treat the flight-time hint as a reason to look closer, not as the measurement itself. The closer look is still a side-on video and a coach's eye on whether the hips are rising or driving through.
A single 2D camera can report how long a runner is in the air and on the ground. It cannot measure how high the body actually rises in that time, since that number needs a calibrated vertical reference the app does not ask for on a running clip.
Time your next meet with the phones you already have
Timing, the Film Room and the speed gates are free forever, with no account. A Club plan, $71 a month, puts your meets on your own results page, and one plan covers every phone.
Related
Why does my sprinter's head bob up and down when they run?
A visible bounce is usually the same fault as overstriding, seen from a different angle, and it is fixable with the same two drills.
Read →Why does my sprinter's stride get longer but their time doesn't improve?
A longer stride on video is not the same thing as a faster stride, and the gap between the two usually shows up in ground contact time, not in the tape measure.
Read →Why does my runner look like they're sitting down when they run?
A hip that never fully opens leaves the foot landing out in front of the body on every single step, which reads on film as a braking force, not just an odd-looking posture.
Read →