Are you sure about running 20km in a match ? The accuraccy of this volume estimate is pretty critical for designing the endurance part of a training programme.
A match is 80 minutes playing time (4x20 minute quarters according to wiki).
This means the player covers 10km per 40 mins, which is a respectable time for a recreational runner racing 10km non stop !
Top soccer premier league players in the UK cover 10km in a match.
I wonder therefore if an AFL player is closer to covering 10km rather than 20km.
Should the training regime therefore be based on a soccer player protocol in terms of distance covered and type of training speeds.