The lunge test is being used more often to assess ankle joint range of motion as it is done in weightbearing and weightbearing assessments are assumed to be more reflective of dynamic function than doing non-weightbearing assessments. There no definitive research on what the normal range of motion that there is for the ankle joint when doing the lunge test and there are also indications that there is no “normal” range as what is normal varies from person to person.
Having said that, the normal range of motion is if the tibia can angle forward over the foot is often assumed to be from 30 to 38 degrees, or around those figures.
The only rider on this is that it may be normal for barefoot, and it may not be normal if wearing shoes, that probably on average have a 1 cm or so heel raise. It has been recommended that the lunge test be done in shoes rather than barefoot. It is quite commonly noticed clinically that someone may be restricted in the lunge test barefoot, but when it repeated wearing shoes, the range is quite normal.