There are events without elevation gain such as motorboat races, open water swimming, or even city marathons. You can now use the elevation diagram as a line showing the progress without ups and downs. The 1D-feature makes competitions with laps more understandable for spectators.

Swimming contest with 1D line and with "normal" elevation chart below. 

Sample event: https://racemap.com/player/21_22-WAOWS-race5

You set up the elevation chart in the tracking map section of your basic tab. Select 1D progress line.