Can you check a sprinter's form on a treadmill with the Film Room?
Most of what the Film Room measures does not care whether the ground is moving, but the one number that needs real distance is the one thing a treadmill never gives up.
Wet weather or an indoor season pushes a sprinter onto a treadmill sooner or later, and the question that follows is whether filming them there actually tells a coach anything real.
What still works
- Trunk lean, because it is an angle read off the skeleton in each frame, not a measurement of how far the athlete travelled.
- Elbow angle, for the same reason.
- Overstride, because it compares where the foot lands to where the hips are, not where the athlete sits on a track.
- Ground contact time, flight time and cadence, since all three come from counting frames between events rather than distance covered.
What does not
Top speed works differently. The Film Room calculates it from two marks a known distance apart, which assumes the athlete is actually covering that ground between them. On a treadmill the athlete barely moves within the frame no matter how fast the belt runs, so there is no real stretch of floor for two marks to measure anyone crossing. The belt's own speed display is the honest number in that case, not anything a side-on camera can work out.
There is one upside to the treadmill that outdoor filming does not give you for free: the athlete stays in the same spot in the frame, so a coach is not panning the phone or losing someone off the edge of the shot, which beginners filming outdoors do constantly.
A single 2D camera reads joint angles and timing the same way whether the ground underneath is a track or a belt. What it cannot do on a treadmill is tell you how fast the athlete is actually moving, because the one number that needs real distance is the one thing a treadmill never gives up.
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 is my sprinter's ground contact time longer on one side?
It might be a real limp worth checking. It might also be a question the Film Room cannot currently answer, because the number it reports is not split left from right.
Read →What frame rate do you need to film a sprinter?
Ordinary video is fine for checking posture. Ground contact time and cadence need enough frames to actually catch the foot going on and off the track.
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 →Try it: Running form analysis app: skeleton, form check, speed and cadence from a phone clip