The profile graph
The graph below the map plots one value along the route.
What the graph shows
It plots the selected Y value over the selected X value for the current position list.
Show or hide it
View → Show Profile toggles the graph on or off.
Choose the X axis
View → Show on X-Axis switches between Distance and Time.
Choose the Y axis
View → Show on Y-Axis switches between Elevation, Speed and Heart Beat. A value only appears if the positions carry it — fill in elevation with Position → Complete… → Elevation. See Complete elevation data for how that works.
Right-click inside the graph
The same Show on X-Axis and Show on Y-Axis submenus are available from a right-click inside the graph.
Print it
File → Print → Profile… prints the graph.