The activity details screen allows you to view all details for a given track. You use this to analyse a horses perofrmance for a recorded session.
Fastest furlong section
This displays the sectionals for the fastest lap if you have a finish point set, or the fastest 1x and 2x furlongs from any section of the track if not finish line was set.

Heart rate vs Speed graph
This graph plots the speed in km/h with the heart rate in beats per minute.

This graph is used to spot how well the horses heart responds to speed work, a fit, healthy horse will show a heart rate that responds very quickly to change in speed, as speed increases, so too does the heart rate, and when speed drops, so to does the heart rate. Heart rate recovery is also easy to spot, when a horse has completed its speed work for the day, a fit horse will have a heart rate that drop dramatically after it is pulled up from a gallop, whereas an unfit horse will show a much more gradual drop in heart rate.
Location
The Location map shows the track recorded for the horse. The colors used to draw the track represent speed zones, ranging from darker colors (brown,blue) for slower speeds to brighter colors (pinks/reds) for faster speeds.
the speedzone colors are as follows:
> 65km/h: Red
58-65km/h: Magenta
50-58km/h: Pink
43-40km/h: Maroon
36-43km/h: Brown
29-36km/h: Blue
<21km/h: Black