In Race mode, you can select the start method you would like to use. Either Starting Gun or Motion Start. In Starting Gun mode, SplitFast will measure the time delay between when the Gun fires, and when you leave the blocks, this is your reaction time. In Motion Start mode, you decide when you want to begin running, so the system begins timing as soon as you leave the blocks. Both methods can give you different information about your performance. Starting Gun is good to simulate actual race conditions, and Motion Start provides consistent repeatable conditions to compare your performance over multiple trials.