Don’t cross the finish line!
Most people have heard not to cross the finish line when you’re not racing, but many don’t know what it’s all about. In order to keep track of laps, OBRA has a camera set up that takes a picture every time the plane of the finish line is crossed, then officials manually note which numbers passed when.
[Aside: This is why they ask you not to sit up whenever you’re crossing the finish line on a lap, as it obscures your number and can affect scoring. Additionally, if you’ve ever been left out of the placing on the sheet after the race or have been shorted a lap, it’s usually because your number was obscured and they have to go back later and try to figure out who you were. So always check the results the next day, because they close results 24hrs after posting.]
So when you are warming up and cross the finish line you cause the camera to fire and this messes up their setup process.
How to get around? Usually there’s a stick on the other side of the line that indicates the boundary of the camera sensor.
Be good citizens, Subs, and avoid the finish line on warm-ups!